|
The Baldwin Library
University
S orida.
NEW .
PHYSICAL Al
q
G O G RAPHY9
FOR 6.
GRAMMAR AND HIGH SCHOOLS, AND COLLEGES
_. ,
;J,
"ti
Bv JAMES MONTEITH
AUTHOR OF PEOGRAPHIES, ATLASES, ]AAPS, EASY LESSONS IN POPULAR SCIENCE,;.
AND POPULAR SCIENCE LEADER
A. S. BARNES & COMPANY ..
NEW YORK AND CHICAGO
grtr %
MONTEITH'S NEW PHYSICAL GEOGRAPHY.
PREFACE.
"T HE attention of Teachers and School Officers is respectfully called to the following
special features of this book :-
Its Easy Style and the Clearness of its Stateeents fit it for use not only in
Grammar Schools, but also in High and Normal Schools.
The Illustrations, executed by the best artists, serve not only to embellish the
work, but to impress vividly upon the mind of the learner the leading truths in this
:most interesting science.
The Text contains the latest discoveries in Phy!siofqraph/y, Mll,,oroloipjy, IHydrog-
raphy, Miagnetism, and Vilcanology.
The Maps and Charts have been compiled from original sources, and from the
.latest official maps of the United Statqs and British Governments.
The subject of lMag!ntism, contains much new matter never before published, the
-material having been obtained from the records of the United States Magnetic Observa-
"tory by the courtesy of Professor Marcus Baker.
The chapter on Volcanoes is based upon the researches of Professor Judd, the
highest authority on the subject of Vulcanology.
The subject of Ocean Currents contains the latest discoveries, including those
made by Commander Bartlett, of the U. S. Steamer Blake.
The chapter on Rivers and Drainage contains much that is new in the way of
Hydrography. The facts and figures have been obtained from the records of the U. S.
Engineer Corps.
The subject of Winds is based upon the researches of Professor Ferrel : that of
Storms, upon the records of the United States Weather Bureau. The latter subject is the
most complete exposition of the Law of Storms that has yet appeared in a school
text-book. It contains new and important principles.
It is the only Physical Geography containing Bird's-eye Relief Maps.
A. S. BARNES & CO.
Copyright. 1835, by JAMES MONTEITH
0 CONTENT S
OfAPTER PAGE'
I.-TEE EARTH IN SPACE. Its Motions, etc. 5
II.-THE CRUST OF THE EARTH. Its Strata, etc. 11
III.-THE LAND SURFACE OF THE EARTH. Its Continents, etc. 20
IV.-MOUNTAINS, PLATEAUS, AND PLAINS 29
V.-ISLANDS. Reefs, Lagoons, etc. 3(
VI.-MAGNETISM. Tie Mariner's Compass;.Magnetic Stnorms, etc. 40
VII.-VOLCANOES AND VOLCANIC FORCES. Phenomena ,of Eruption; Geysers, etc. 44
VIII.-EARTHQUAKES. Their Causes and Effects 51
IX.-THIE WATER OF THE ATMOSPIIEE. Its Forms and Uses 56
X.-THE WATERS OF THE CONTINENTS. Springs and Lakes 62
XI.-RIVERS AND DRAINAGE. What Rivers are and what they do 6S
XII.-AVALANCHIES, GLACIERS, AND ICEBERGS. Their Formation and Powers. 75
XIII.-OCEAN WATERS. Their Extent, Color, Waves, etc. 81
XIV.-TIDES. What Causes them 86
XV.-OCEAN CURRENTS. Their Formation and Influence 90
XVI.-THE ATMOSPHERE. Its Properties, Winds, Calms, etc. 9(i
XVII.-STORMS, CYCLONES, AND TORNADOES. Their Nature and Effects 102
XVIII.-CLIMATE --------- 109
XIX.-THE DISTRIBUTION OF LIFE 11
XX.-MINERALS 130
APPENDIX.
RELIEF MAPS. RECORD OF RECENT DISCOVERIES, Etc. 136
C'
JUPITER
/- ..
.
.. .5.TURN
-F
SNEPTUNE .--
THE SOLAR SYSTEM.
i diagram showing the paths and relative rize of the variouLS members a; the Solar System.
he spe Orbit of Saturn represents the ortionate ize the Sun.
1 ~ --- -- ___- -;.. -
Hi I o-i *
~-_e SPiLc3 :.: : "" :7"." Orbit of Saturn *epres-nts tks propotio,e siz oS the Sun.
PHYSICAL GEOGRAPHY.
CHAPTER I.
* TH E EARTH IN SPACE.
1. Stars.-Those bright, twinkling points of
light that we see in the sky after the Sun has
gone down, are huge balls of matter.
2. All of them are very far away, and some
are so distant that a ray of light, moving 186,000
miles every second, would not reach the earth for
many years after starting on its journey.'1
3. Nearly all of these heavenly bodies are
many times hotter than the hottest furnace-fire- m
so hot, indeed, that they exist either as molten
matter or else as a vapor.'
4. A few of these balls of matter are con-
stantly changing their position in the sky. They
no longer give light of their own, but we see them
because the light of the sun falls on them, and is
reflected to our eyes. The Earth in Space.
5. They are called planets (from a Greek word meaning wanderer), and they are for-
ever whirling round and round the Sun.
6. The Earth is one of these Planets.
7. Fixed Stars.-The Sun gives both light and heat to the family of planets whirling
around him. The other bright bodies are called fixed stars. The Sun is one of them.
8. All of the other Fixed .htr, are suns, and there are many reasons for believing that
each has a family of worlds or planets revolving about it.
S The nearest fixed star, excepting the Sun, is star 61 of the constellation Cygnus. Its light is seven years in reaching
the Earth.
I Every substance exists in at least two of three states-solid, liquid, or vapor. By heating iron it melts, and finally
Soils, giving off an orange-brown vapor or steam. Water may be easily changed to ice or to steam. By withdrawing the
e '-at, and at the same time applying great pressure, the air we breathe has been liquefied.
6 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
9. Our Sun and his group of worlds is called The Solar System.
10. The Solar System is composed of the Sun, eight worlds called planets, twenty
satellites or moons, and about 240 smaller planets called asteroids, besides comets and
meteors.'
THE SOLAR SYSTEM.
DISTANCE FROM MOVES AROUND SUN DIAMETER, NO. OF
EMBERS OF SYSTEM. I SUN, ONCE IN IN MILES. MOONS.
IN MILES.
SUN. .............. ..... ........ ........ .. ... ...... 860,000 ...
Mercury.................. 35,750,000 88 days. 2,992 0
Venus..................... 66,750,000 224 days. 7,660 0
Earth.................... 92,300,000 1 y. 7,918 1
Mars ...................... 141,000,000 1.9 y. 4,211 2
Asteroids.............. ....... ..... ..... .........................
Jupiter.................. 480,000,000 11.8 y. 86,000 4
Saturn................... 881,000,000 29.5 y. 70,500 8
Uranus (f'ra-nus). ........ 1,771,000,000 84 y. 31,700 4
Neptune.................. 2,775.000.000 164.8 y. 34,500 1
11. Between Mars and Jupiter are about 240 small planets, called asteroids. They are
very small, none exceeding 300 miles in diameter.
12. Since the year 1600, more than 200 comets have been discovered.
13. A few comets belong to the Solar system, and travel around the Sun very much as
the planets do. Others came from regions in space of which we have no knowledge, and
after passing partly around the Sun, went off into space, never to return.
14. Meteors are commonly called shooting stars. They may be seen on almost any
clear night, darting like balls of fire across the sky.2
15. The planets in their order from the Sun, are named as follows : Mercury, Venus,
Earth, Mars, the Asteroids, Jupiter, Saturn, Uranus, and Neptune.
16. The line in the diagram on which each planet is situated shows its path around
the Sun.
17. All of the planets move around the Sun from west to east.
18. Their orbits or paths are ellipses, the Sun being at one focus or center.
19. Each of the planets turns on its axis from west to east.
SThe velocity of meteors is about forty miles per second. Moving with such a great velocity, when meteors strike
the Earth's atmosphere, the great heat developed not only melts, but vaporizes all but the largest ones. Many fall to the
Earth and are found. Some are composed chiefly of iron and nickel. Others are of the nature bf stone. At least one comet
(Tempel's) has been proved to consist of an immense swarm of meteors moving in a cluster around the Sun.
It is usual, but hardly correct, to say that the planets revolve about the Sun. The truth is that all of the members.
of the Solar System revolve about a common center of gravity.
THE EARTH IN SPACE. 7
20. The Earth and each planet beyond it are attended by one
or more moons.
21. Each moon moves around its planet in an elliptical path
from west to east.
22. So far as known, each moon turns on its axis from west
to east.
23. The Earth. and probably the other planets, are composed
of the same elements that are found in the Sun.' Of many
meteors that have been analyzed, none has been found which con-
tains elements other than those which compose the Earth. Telescopic View of Jupiter.
24. Thus it will be seen that the planets,in many respects,resemble one another."
* 25. They differ widely in their physical condition, however. Some are apparently hot
.and fluid, while others are cold and solid.
26. Jupiter is still glowing with heat, and possibly gives a faint light to its four moons.
It is enveloped by dense clouds forming the bands or zones, which are seen in the picture.
27. Saturn is surrounded by several flat rings,
one outside of another, whirling swiftly around as
S- though they were the rims of immense fiery wheels.
It is thought that Saturn is a world yet in the process
of formation, and that the matter composing this
planet is partly fluid and partly solid.
28. Mars is a world very much like our own. Its
surface is diversified with oceans, seas, bays, conti-
nents, islands, and peninsulas. Through a good tele-
Telescopic View of Saturn. scope one may see the frozen zones of ice and snow,
one at the north, the other at the south pole. Its
"position, with respect to the Sun, is such that the temperate zones of Mars have seasons
like ours.
29. The Moon.-At least one of these heavenly bodies, the moon, has become cold from
surface to center. The air and water, if ever there were any, have disappeared. Its surface
is covered with immense craters, many of which exceed fifty miles in diameter. During the
hottest part of the moon's day, the temperature is nearly that of melting lead; at night, it is
thought to be about 2000 below zero.
30. The Sun.-The Sun is a huge mass of matter more than 1,250,000 times greater than
SThis has been discovered by analyzing the light of the Sun with the spectroscope. Sodium, potassium, iron, nickel,
hydrogen, and many other elements have been discovered in the Sun, and most of them also occur in several fixed stars.
SIt is thought by many students of nature, that all of the matter which composes the solar system was originally in
one mass of vapor; that this matter began to gather around a center; that a rotation around this center was acquired;
that the mass of revolving vapor grew smaller in bulk as it cooled; that finally,the rotation became so rapid that portions of
the mass were thrown off; that these portions, collecting in globular masses, formed the planets ; and that the planets, by
a similar process, threw off still smaller portions, which became moons. Although this is a supposition only, yet there are
many facts which make it worthy of belief.
8 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
N the Earth. The spectroscope shows that it is
composed of substances similar to those found
in the Earth and the other planets.
31. These substances, however, owing to
the intense heat, are at the surface, in a gas-
eous or a fluid state.
32. With a powerful telescope,jets of gas
at a white heat may be seen projected to a
S a 1 E distance of even 200,000 miles. The velocity
with which these immense columns of gas are
thrown upward, sometimes exceeds 250 miles
per second.
33. Sometimes, funnel-shaped, black spots
are seen on the Sun's surface. These spots
have exceeded 140,000 miles in diameter.
They are usually in violent agitation. In-
deed, the whole surface of the Sun appears to
8 be a tempestuous sea of white-hot metallic
Telescopic view of Moon. vapors, and seething, molten elements.
34. In shape,the Earth is a slightly flattened sphere, bulging at the Equator.' This
has been shown in various ways.
35. Ships have sailed around it. The Earth's shadow is circular. A straight line sur-
veyed at the surface of the water apparently rises. In reality, the surface of the Earth
curves away from the line.
36. The Dimensions of the Earth are
as follows :-
Diameter at the poles, 7899.2 miles.
Diameter at the equator, 7925.6 miles.
Circumference at the equator, 24,899 miles.
Surface, 197,000,000 square miles.
Volume, 260,000,000,000 cubic miles.
37. The Earth weighs about five times
as much as a globe of water of the same size.
Its density, therefore, is said to be 5. At the
surface, however, the density is only about 2 ;
that is, a cubic foot of matter composing the -
surface is only 2.- times as heavy as the same Sun Spot. The size of the Earth is shown in one corner.
bulk of water.
38. Hence it is thought that either the matter in the interior of the earth is compressed,
or else that it is composed of metallic substances.
1 In mathematics, such a solid is called an oblate spheroid. The Earth is not a true oblate spheroid, however, as recent
investigations have shown that there is also a slight bulging at the temperate zones. This square-shouldered appearance
is also noticeable in Saturn and Jupiter.
THE EARTH IN SPACE. 9
39. The pupil who studies
the rocks that compose the sur-
face of the Earth will contin-....
ually find fresh proofs that the
whole Earth was once at a glow-
ing white heat.1
40. Motions.-There is
nothing at rest in the Universe.
Suns, moons, and planets are t Ei
constantly whirling about their :. -
common center, and all are at ,
the same time sweeping on
through space. The stars, too,
are in swift motion, each in his
own path, never for a moment
resting...............
41. Tire Earth has two
T E An ellipse, representing a distorted view of the Earth's orbit. E is the Earth; F is one
motions. First, it turns on its focus of the ellipse; the Sun is at the other. The Earth is 8,000,000 miles nearer the
axis, causing day and night.2 Sun at perihelion, than six months later.
Second, it moves rapidly around the sun, making the complete journey in about 3651
days.
42. When nearest the Sun, the
Earth is said to be in perihelion;
when farthest from the Sun, in
aphelion.
43. The Earth reaches its peri-
helion about January 1st and its
aphelion, six months later. Its mo-
B tion is most rapid while in. peri-
helion.
44. The axis of the Earth is in-
clined 231 degrees toward the eclip-
The Succession of Day and Night. The lamp represents the Sun; the apple, the tic, as may be seen in the diagram
Earth; the needle on which the apple turns represents the Axis of the Earth, at the top of the next page.
SAlthough the temperature of the Earth's interior is far above the melting point of the most refractory substances,
it is by no means certain that it is in a fluid condition. On the contrary, the Earth, with respect to the Sun's attraction,
behaves like a solid body.
2 The time required by the Earth to make a complete revolution is divided for convenience into twenty-four hours.
At the equator, the circumference of the Earth is nearly 25,000 miles, but the parallels decrease rapidly in length as they
approach the poles. It is evident, therefore, that the velocity diminishes as the latitude increases, being greatest at the
equator.
In latitude 0', the velocity is 1,040 miles per hour; in latitude 30', 896 miles; in latitude 50%, 665 miles; in latitude
70', 354 miles; in latitude 80', 180 miles; and at the poles, it is 0.
3 The length of this journey around the sun is about 580,000,000 miles. This divided by 365- x 24 gives a quotient of
about 66,000 miles, the Earth's velocity in miles per hour. The velocity in one second is nearly 19 miles.
There is one other motion of the Earth, which, in great lengths of time, is thought to modify its climate. The poles of
the Earth are constantly moving around in a circle, in the same manner as does the upper pole of a sleeping top. This move-
-ment is completed in 27.000 years.
10 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
The Earth's orbit as it would appear if viewed on a level with the Ecliptic, or plane of the orbit.
45. From the illustration on the preceding page, you will see that the Earth is nearest
the Sun during the winter of the Northern Hemisphere, where most of the land is situated.
46. The effect of this is not only to temper the extreme heat of summer, but also to
moderate the cold of winter in this hemisphere.
47. In respect to its distance from the Sun, the inclination of its axis, and its velocity,
the Earth seems better adapted than any other planet for the sustenance of life.'
WHAT HAS BEEN TAUGHT IN CHAPTER -I.
The stars are great masses of intensely hot lost, if not all of the )plaets are surrounded
matter many million miles away. by (ti atmtoosphere.
The nearest fixed star is the S,,u. The emotions of each planet are principally ar
The San is attended by eight planets and spintinf; upon its axis and a thirling around
about 240 asteroids that are continually whirl- the Sun.
ing about it. The Earth measures about 25,000 miles in
( ircuiinference, and nearly 8,000 miles in di-
There are also comets, some of which are a
i ameter. Its distance from the Sasn is nearly
part of the solar system, and innumerable me-
teors or shooting stars. 3000,000 i
It spiits ons. its aris about 3(65 times while if
lost of the planets hare cooled antd no longer t
mores around M the Suni once.
give any light, but others are thought to be still
"The first of these is the cause of the succes-
in a fluid condition, and perhaps to emit a faint of da and )light, the o cases he
sion of daj/ and night, the second causes the
light.
light, change of seasons.
All the planets are like the Stin in shape, (and In its journCey around the Stun, the Earth
they resemble one another in their motions d os a m at the rate of 66,000 miles per hour.
general properties. The path of the Earth is tan ellipse, the Sun
All but two of them are attended by nmoons or being at one of its foci or centers.
satellites, havtinig form (and motions like the The Earth is about 3,000,000 miles nearer
planets themselves, the Stuni itn i'inter thia in suitmlmer.
S We shall learn in chapters following, that life-forms have played an important part in the history of the world.
Many of the rocks have been formed through their agency; the present aspect of the Earth's surface is largely owing to the
work of plant and animal life. We need go only a few miles, either above or below the Earth's surface, to find conditions of
cold or of heat that would at once be fatal to any form of life with which we are acquainted. Yet, through all the changes
and convulsions of nature, life-forms have not only held their place, but they have also steadily progressed to higher and
more complex stages. How life came upon the Earth, in what form it first appeared, and why it has developed into such
various forms, are questions which we cannot answer.
THE CRUST OF THE EARTH. 11
C CHAPTER II.
THE CRUST OF THE EARTH.
1. It is thought that the Earth was once a seething, molten mass, and that through the
course of long periods of time, the surface gradually cooled, until a solid crust formed on
the outside.'
2. The thickness of the cooled crust of the Earth is estimated at from 55 miles to 250
miles. There are at the present time, however, no means whereby it may be measured with
any certainty.
3. Condition of Interior.-That the interior of the Earth is intensely hot, there is
little or no doubt-a fact which may be shown by several phenomena.
4. First, the shape of the Earth, slightly flattened at the poles, is such as would be
produced by the spinning of a partly fluid body on its axis.
5. SeEond, active volcanoes are found in all parts of the world. These throw large
quantities of melted matter from their craters.
6. Third, in sinking deep shafts and artesian wells, there is a gradual increase of
temperature, averaging 1 F. for about 53 feet.'
7. Fourth, geysers and hot springs occur at various latitudes in every continent. The
waters of these springs sink deep into the Earth through crevices and passages. When they
return to the surface, these waters are heated nearly or quite to the boiling point. Hence
they derive their heat from the Earth's interior.3
8. Formative Processes.-The student who studies the crust of the Earth will readily
believe that long periods of time have elapsed since the Earth took its present form.
1 Whether or not the interior of the Earth is in a fluid condition, is as yet a matter of speculation. The stronger
evidence certainly leads to the conclusion that the Earth is solid, or else plastic, from center to surface. Many mathematicians
are of the opinion that the great pressure from the outside towards the center-that is, the enormous weight of the overlying
crust-causes the heated interior to retain a condition of rigid solidity.
2 This increase in temperature is by no means uniform, but varies between 27 and 198 feet per degree. The rate of
increase is greater in mines than in artesian wells. In many instances, the rate of increase is very largely due to the heat
resulting from chemical decomposition. For instance, in the deep shafts of the Nevada silver mines, the temperature, on the
same levels of different mines, varies from 10' to 600. Beyond a depth of 2,000 feet, the average rate of increase is 1 for
every 165 feet.
The thickness of the Earth's crust cannot be estimated from these figures, however, as the melting point of solids
varies with the pressure-the greater the pressure, the higher the melting temperature. Besides, the crust of the Earth has
never been penetrated more than one mile in depth, and it cannot be told whether or not the increase of temperature is the
same for all depths.
3 In many instances, however, hot springs derive their heat from the chemical changes going on among the rocks.
12 MIONTEJTH'S NEIV PHYSICAL GEOGRAPHY.
9. Nearly. if not all, of the dry
Island has been again and again cov-
ered by the waters of the sea, and we
Smay also believe that what is now the
bed of the ocean has been more than
once lifted above the surface of the
-- waters.
h 10. Plant life in the greatest
luxuriance, and most wonderful in
form and size. has covered the face of
Se Earth and has been overwhelmed by
the waters.
- 11. Gigantic animals lived,
n multiplied, and perished. Enormous
S reptiles inhabited the immense swamps
and morasses which, during different
i periods, covered large areas of the
Earth's surface. These perished, and
The parts of the map shown in white represent the first land of the United States. were succeeded by other forms of life,
The parts in dark shading along the coasts remained under water until a more and these, in turn, passed away, leav-
recent period.
The dark shading inland were vast tracts of marsh and woodland, but now they are ing the story of their lives printed
the great coal fields of this country. upon the rocks.
12. Different climates succeeded one another. Parts of the Earth, at one period
covered with ferns, palms, and other tropical plants, were afterwards buried under the ice
and snow of a dreary winter that for centuries chilled the Earth's surface.
13. Immense glaciers, or rivers of ice, have rounded off the sharp hilltops and moun-
tain sides, and have ploughed deep gorges through the hardest rock.
14. Earthquakes andi upheavals have raised large surfaces of land out of the waters,
and in other places, have sunk great areas until the sea covered them many fathoms deep.
15. Volcanoes and fissures have poured out floods of lava until immense areas of ter-
ritory have been covered to a great depth.1
16. Running waters have worn their way through these sheets of lava and other
rock, cutting channels, sometimes exceeding a mile in depth, into the mountains and
plateaus.
The winld, blowing loose sand and dirt day after day and year after year, has filled up
seas, and in some cases has severed arms of the sea from the main body of water. Often it
has extended the shore for miles into the sea.2
17. These changes, carved in the rocks by the forces of nature, have been going on for
ages. No one can measure the time in years; it can be measured only in periods of un-
known length.
I One of the most remarkable lava floods is that of the northwestern portion of the United States. It covers an area of
about 200,000 square miles in Oregon and Washington. This sheet of lava, where the Columbia river has cut through it, is
nearly 4,000 feet thick.-Le Conte.
I At Pescadero, California, an ancient sea beach, has been found two and a half miles inland from the present shore.
The whole intervening area has been filled by sand driven before the wind.
THE CR UST OF THE EARTH. 13
18. Rocks.-By the term rock,
is meant anything that enters into
the structure of the Earth's crust.
Sand, clay, gravel, granite, limestone
and slate are all classed as rocks.
19. For the convenience of stu-
dents, rocks are classified in several
different ways. The following are
the most commonly mentioned:
Igieois Aqueous
or and or
Unstratifiedl, Str-tified.
Fossiliferous,
Metamorphic,
Primary, Secondary, Tertiary, Etc.
20. Igneous rocks are those
which have been formed by the ac-
tion of heat. They are usually (ex-
cept lavas) found in dikes or irregular
veins. Frequently, they have a glassy j:-
lustre. Lava. pumice-stone (volcanic -
froth), and trap-rock are examples.
Igneous rocks are unstratified.1
21. Aqueous2 rocks are formed
out of the sediments that have been
deposited by water. They are usually Work of Waves. Fjord in Norway.
soft, and have a clayey appearance.
Aqueous rocks are always stratified.
Sandstones, limestones, claystones,
"-: -- -and slates are examples.
"22. Stratified3 rocks are of
aqueous origin. They are so called
'I, .because they appear in sheet-like
masses called strata, each stratum
having a uniform thickness. Strati-
-- ,fled rocks may usually be split into
thin sheets or layers.'
SThe teacher should procure good specimens
j-j of each rock mentioned Typical specimens may
hbe purchased for a small sum of money. In many
.. localities they may be found in large quantities.
In mountainous countries, it will frequently hap-
Igneous Rocks. Finugal Cave. pen that all the rocks here described may be found
near the school house.
Aqueotus, from the Latin, aqua, water ; hence, rocks formed by the action of water.
Stratified, from the Latin, stratum, a layer; hence, rocks arranged in layers.
The thin layers into which stratified rock may sometimes be split are called laminate. Not all stratified rock is capable
of being thus split up.
14 MONTEITH'S NVEW PHYSICAL GEOGRAPHY.
23. Slate, soft coal, many sandstones,
and sales are examples of stratified rocks.
_77^ ..... \ \e 324. Unstratified rocks do not occur in
/ -- layers. They are rocks of igneous origin.1
25. Aqueous rocks are frequently
Stratified Rock.
called sediments, or sedimentary rocks.
26. The fine mud which running water often contains is called silt. The Missouri and
the Sacramento river hold in suspension,large quantities of silt.
27. Metamorphic2 rocks are thought to be sediments, which, under great pressure,
have been changed by the combined action of heat and water, until they resemble igneous
rocks.
28. Metamorphic rocks are generally composed of crystals, irregularly cemented
together. Sometimes they appear to have been partly melted. Gneiss, clayslates, and
marble are examples.3
29. Fossiliferous rocks are stratified rocks which contain the casts or "petrified
bodies" of animals or of vegetable growths.
30. In limestone, the stone form of the animal or plant appears as though it had been
cast in a mould.
31. In sandstone, however, usually the print or impression only, is found.
32. Among these imprints and casts, are found the tracks of reptiles and birds, the
stony skeletons of huge animals, and the delicately drawn pictures of leaves and insects.4
33. Stratification.-Except where igneous rock has been thrust to the surface, the
surface of the continents is covered with sedimentary or aqueous rocks.
34. The various strata were, at first, in horizontal layers; but on account of the con-
traction of the Earth's crust in cooling, they are frequently in an oblique position. Some-
times they occur in folds, and often they are greatly crumpled and broken.
S"Beds of mud, clay, or sand may often be traced, by insensible gradations, into shales and sandstones. In many
places, the process of consolidation is going on before our eyes. . Thus, the sediments of the Rhine are now consolidating
into hard stone, and, on the coast of Florida and Cuba, comminuted shell and corals are quickly cemented into solid rock."-
La Coote.
Pupils living on the sea shore, may sometimes see the process of stratified rock making. The water of an incoming
tide is loaded with mud and ooze. At the turning of the tide, the mud and ooze sink to the bottom, and as the tide
slowly recedes, are baked and hardened by the sun. The next incoming tide bears a fresh deposit of mud, which, in turn,
hardens. Shellfish are frequently caught between layers, and birds sometimes run over the fresh, soft surface. Both shellfish
and bird-tracks are covered by the next deposit which the tide bears. Thus, a permanent record is made, which may be read
ages hence.
2 Metamurphic, from a Greek word meaning change or transformation.
3 Granite is also classed among metamorphic rocks. The minerals composing granite are mica, feldspar, and quartz.
Whenever granite is stratified or laminated, it is called gneiss. If the feldspar is wanting, it is mica schist. If the mica is
replaced by hornblende, the rock is then called syenite.
Sandstone is composed of small grains of sand cemented together by lime, magnesia, or by oxide of iron. The brown
stone of New York is a sandstone of the latter class. Sandstones are frequently metamorphic.
These casts are usually called "petrified" remains or bodies. The substance itself does not turn to stone; it is
gradually absorbed, and the cavity is, at the same time, filled from the surrounding rock.
THE CRUST OF THE EARTH. 15
35. In some localities, where strata have
been tilted, or turned with their edges up-
ward, fresh layers of aqueous rock have been
deposited on the upturned edges of the first.
Strata in this position are said to be uncon-
formable.
Strata folded by Side Pressure.
36. The process by which the edges of
strata have been laid bare through natural causes, is called erosion.
37. It is in this way that the book of the world's history has been opened so that the
story may be read from its pages. Each
stratum is a chapter in the story of the -
world, and the student will at once see
-why we begin to read at the lowest.
38. It is not always easy to deter-
mine the relative position of strata at
a distance from each other. It has
taken many years to learn the little
that is already known.
39. Now, the position of strata
*can generally be told by the fossils :
.contained within them, and the differ- :
ent groups of strata are named from _
the character of the fossil plants and :
animals they contain.
40. Thus, the rock lowest in rela-
tive position is called the rock of the
Azoic (without life) era.'
41. Order of Strata.-Upon this "
is found the rocks of Palceozoic (early
life) era. Then comes the Mlesozoic
(middle life) era. Next above is the
Cenozoic. (new life) era. Last of all is
the era in which inall appeared on
the Earth.
42. On page 16 the pupil will see
the arrangement of the various ages
as they occur. Each age is subdivided
into periods and epochs."
43. Azoic Life.-- In the Azoic I
era, no forms of life are with certainty P"
known to exist. It is thought, how-
ever, that life of some kind, probably t+
vegetable, had appeared even then. Erosion.-Work of Rivers.
Fossil remains have recently been found in Azoic rocks.
SThe series of strata is never found complete in any one place, as it appears in the table. In one locality, the Azoic
rocks are found at the surface ; in another, secondary; in still another, tertiary, or perhaps secondary. The relative position
was first determined by noticing the overlapping of the edges. Now the geologist can determine the age or the period by
the character of the foils.
16 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
ERA. AG-E. PERIOD.
PSYCHOZOIC. AGE OF MAN.
CENOZOIC AGE OF
ERA. MAMMALS. All "
I I I :,;," / /
MESOZOIC AGE OF i
ERA. REPTILES.
CARBONIFEROUS:
O AGE OF Showing rocks of different periods at the surface.
COAL.PLANTS
AMPIIANS. 44, Palmozoic Life.-In the lower strata of
o0-- the Palaeozoic era, there are found a few sponge-
DEVONIAN; like animals. These had no special form, and were
N nothing but jelly-like substances, having neither
AGE OF limbs, head, nor digestive organs.
o FISHES. 45. Silurian Life.-Above these strata in the
I= Palaeozoic time are found the rocks of the
SSILURIAN 46. Silurian Age, or the age of shell-fish. Of
"< AGE OF these,there were a great many species.
.- SHELL FISH,
AZOC ERA :L'E f.I1 C- .,
EOZOIC OR Fir. T rI.i, _
Order of Strata. Fossil Coral.
47. Corals, sponges, and star fish were abundant. The sponges of the Silurian age were
more highly developed than those of the previous time. A few mosses and lichens existed.
48. Devonian Life.-The Devonian age succeeded the Silurian. This is the age of
fishes, during which, for about the first time, an animal having a backbone appears on the
Earth.
49. Shell-fish were still abundant, and they were also of a higher type. Corals were
less plentiful.
50. Land plants and forest trees thrived, and, for the first time, insects existed. The
Devonian age passed almost insensibly into the
51. Carboniferous Age, the period when coal plants and amphibious' animals began
their existence. The coal plants, which included horse-tails, tree ferns, and reeds of enormous
size, were the chief feature of this age.
I Amphibious animals are those that live equally well either on land or in water.
THE CRUST OF THE EARTH. 17
Silurian Shell-fish. 3
Devonian Fish.
52. These plants flourished, died, and were covered by the sediments of successive
floods, till, in some localities, the various strata of coal exceed two miles in thickness.
53. Reptiles began to appear during this age. Fish, shell-fish, corals, and insects also
abounded.
54. The climate of the Carbonifer-
ous age was'moist and tropical.
55. Mesozoic Life.-The Mesozoic
era occurred at the close of the Carbon-
iferous age. ii Sandstone.
Coal Bed.
56. Enormous lizard-like rep- oal Bed
tiles, crocodiles, and turtles were the clay.
principal life-characteristics of this era. Iron Ore.
peared. A few species of these are re- MINI Sandstone.
markable for their having, instead of qe
111. ll I Coal Bed.
beaks, jaws set with socket teeth.
=~--~----. -..... .
58. Cenozoic Life.-The Cenozoic Clay.
era, which followed, is the period in ,-
which mammals were the ruling type The coal teams or the carboniferous Age.
of animals. The animals of this era appeared on the Earth with apparent suddenness, and
in great numbers.
59. In the Bad Lands, the plains of Colorado, and other great burial grounds of
animal remains, are found the fossil bones of the elephant, the rhinoceros, the horse, the
wolf, the deer, and many other kinds.
SMammals-animals which suckle their young.
.1--' t
18 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
60. Before the dawn of this era,
S all of the species of gigantic reptiles
t had perished. They were replaced by
smaller species of crocodiles, turtles,
_.i Lt snakes, and frogs.
ST 61. E urope and N north A m erica,
at this time, were regions of perpetual
Laflet en arged. summer. A profusion of tropical plants
flourished, and tropical animals in mul-
titudes lived and covered the Earth.
62. More than 1,500 species of
insects have been found in the rocks
of the Cenozoic era. Ants, bees, wasps,
and butterflies of various kinds are
found in great numbers.
63. Glacial Epoch.--About the
middle of this era, a change of climate
Fern Leaf of Carboniferous Age. throughout the whole northern hemi-
sphere occurred, and the tropical cli-
mate that had lasted so many ages, gave place to one of icy coldness.
64. Thus was ushered in the great Glacial epoch. During this epoch, North America
and Europe were scored in every direction by glaciers which grated over the surface of these
continents.
65. The sharp tops of the mountains
were rounded off, caifons and ravines were
cut deep into the rocks, and the plains were "
covered to a great depth by loose drift
scraped off the mountain sides.
66. With the coming of the Glacial
epoch, large numbers of animal species dis-
appeared from the face of the Earth. There -
survived, however, the cave bear, the cave e-
"lion, the horse, the reindeer, and the wolf. -- o
67. Age of Man.-At last appeared 6-
the crowning glory of the history of cre-
ation-Man. With his coming, the reign of Reptiles of Cenozoic Era.
brute force that had held sway so many ages, ended.
68. In the bone caverns of Belgium, Germany, and Italy, skeletons of human beings
are found with the bones of extinct animals. Scattered about the cavern are rude weapons
and implements of the chase. These caverns are covered up with limestone, over which are
gravel and drift many feet deep.'
SIn England, flint implements associated with the broken and hacked bones of extinct animals, are found above the
lacial epoch, and under the gravel beds of the Champlain epoch.
Only a few years ago an almost perfect skeleton of a Paleolithic man was found in a cave at Mentone, France. It
THE CRUST OF THE EARTH. 19
69. From the few scraps of un- Age. Period. Epoch.
written history which he has left, Tii--.E.
primitive man seems to have been a .
savage of the lowest type. He lived A:C" .O. MA.
s --- -.; AT ar.E..C. A Y.
in caves, and eked out an existence .
by fishing and hunting. He neither < ---f._|e
cultivated the soil, nor did he have u
any domestic animals. ; i :.:E.
70. In the preceding brief history, <
the student will not fail to notice that ___. ... ._ E.'' __
each succeeding age has brought forth
higher and better developed forms of life than those of a preceding period.
71. Improvement and progression have been the law of creation. Each succeeding
chapter of the story sheds a greater glory upon the Great Architect of the Universe, whose
wisdom and power know neither beginning nor ending.
WHAT HAS BEEN TAUGHT -IN CHAPTER II.
The Earth was once a molten mass of matter, letamnorphic rocks are aqueous or sediment-
That the interior of the Earth is yet intensely heat, pressure, tiad water.
hot. Aqueous rocks generally, and metamorphic
The internal heat is shown by volcanoes, hot rocks sometimes, contain the casts or the im-
springs, and the increase of temperature towards prints of animals and plants.
the center. InL the lowest rocks, the Azoir, few forms of
That various forms of animal and plant life life appear.
have appeared d disappeared. In the Palteozoic era, which followed, sponge-
That the whole .tirfirv of the Earth has been like animals, corals, shell-fish, and fish having
changed by the action of water, and also by vol- backbones, appeared in succession.
canic action. In the latter part of this era, huge amphib-
The story of these great changes has been re- ians and the vegetation which formed most of
corded in the rocks, our coal fields, thrived in great abundance.
Rockes are classified as stratified or aqueous, The JMesozoic era, which followed, is noted
unstratified or igneous, metam-orphic, and fos- for the great number of gigantic reptiles, the
siliferous. prevailing types of life during that period.
Stratified or aqueous rocks are formed by In the Cenozoic era, which succeeded, maIt-
the action of water; they occur in layers or vrals were the prevailing type of life.
strata. That man first appeared just after the close
Unstratified or igneous rocks are formed by of this era.
the fusion of the substances composing the Each age has produced higher forms of life
Earth. than those of the ages preceding it.
is that of a well-formed man with an average sized skull, and a facial angle of 8.5' The antiquity of this man is undoubted,
for his bones are associated with those of the cave lion, cave bear, rhinoceros, and reindeer, together with those of living
species. The bones of the skeleton are all in place, surrounded with the implements of the chase (flint implements) and the
spoils of the chase, viz., the bones of the reindeer, perforated teeth of stag, etc. Of the latter, 22 lay about his head. These
are supposed to have been worn as a chaplet. This Quaternary man seems to have laid himself quietly down in his cave
house and died."-Le Conte.
20 A1/OATEITH'S vNET PHYSICAL GEOGRAPHY.
C H A P T E T III.
THTE LAND SUH FAC OF iP T E TARiPTH.
1. Extent. The surface of the Earth
SW.TER covers an area of about 197,000,000 square miles.
-4 _-_-_ Of this area 144.000.000 are water, and the re-
maining 53,000,000 square miles. land.
She lan surface of the Earth consists
of several large bodies of irregular shape, called
continents, together with a large number of
Islands.
.. 3. The islands have an ,-r,-.. area of
--- 3,000,000 square miles.
Comparative Arca. of Oceans, Continents, and Islands. 4. Shape.-These land masses have each a
triangular shape, broad at the north and tapering to a point at the south. They form the six
continents.
5. Position.-The largest continents are crowded about the North Pole, stretching
southward in three directions. The three northern lie almost wholly in the North Tem-
perate, and the three southern, in the Torrid zone.
6. Taking the north of France as
a center, a great circle will divide the /
Earth into two hemispheres, the north- '- / .-
ern one of which contains nearly all / f
the land. A point southeast of New / -
Zealand is the center of the water hemi- --L
sphere.
7. The land surface may be sepa- '
rated into two divisions, which lie on
opposite sides of the Earth. For con-
venience, the two halves of the Earth
are called the Eastern and the Western
Hemisphere.
8. The Eastern Henlisphere The general form of each of the land divisions is that of a triangle, the apex
contains the continents of Europe, pointing toward the south.
Asia, Africa, and Australia, together
with a large number of islands. It contains nearly two-thirds of the entire land surface.
9. The Western Heinisphere contains the continents of North America and South
America, together with many islands.
10. Coast Lines.-Of the six continents, the northern group of three is bounded by a
very irregular coast line. This irregular coast forms a great number of bays, gulfs, and
peninsulas.
T7f I .-1.D R F.!'C; 0 Y TIf ,'--.; AR T. .
AurRAA EUROPE SAMERICA N.AMERICA AFRICA ASIA
o o I I o
I c. 0
C =' 0 0
o a f o
]q _
Relative Size of the Continents, in Square Miles.
17 Such indented coasts are of the
greate-t importance to the people inhabiting CONTINENTs. AREA. COAST SQ. M. FOR
o continent. because the existence of a large LIE. 1M.OFC'ST.
uuml-, r of good harbors, more than any other --
cause. ipr.Imotes a diffusion of industries, Asia............... 17,000,000 35,000 500
kn:owlr,,tLj. and civilization. They also mod- Africa............. 12,000,000 16,000 750
itY andI timper the climate of a country, in- -North America.. 8,400,000 22.800 368
ctreasing ito fertility and productiveness. South America... 6,500,000 14,500 449
fEurope........... 3,700,000 19,500 190
1 TI. TI,. accompanying table shows the Australia......... 3,000,000 10,000 800
relative'. I,.i-Lth of coast to continental areas :__ ___
..
,ii 1
=..
The Distribution of Land and Water.
.1. It will be noticed by this comparison that Europe ranks first, and Africa last. It
might t-ruthlfully be said that the intellectual and commercial importance of a continent
depend- dir,.-ctly upon the comparative length of its coast line.
14. surface.-Continents are not plain, level surfaces. They are diversified with moun-
tains and valleys, plains and rolling hills, table-lands and lake-beds, rugged hills, ravines,
and winding rivers.
22 ZIONTEIVTH'S NEW PHYSICAL GEOGRAPHY.
/* /
/ AREA -
3,7W,000 A E f
AAREAR
17.000,000
SQ. MLS
S I
S, EA
AREA '5 : 00 6 liL"l
S ,00/ I00 ;" -.
69. PO LS '
iiV-
Length of Coast compared with Area. The circumference of the outer circle represents the length of the coast line.
15. Mountains appear in ranges,which are usually of great length.
16. A mountain chain or system consists of several parallel ranges. Thus, the Alle-
ghany, the Blue, and the Cumberland range of mountains, together, form the Appalachian
system.
17. The principal mountain system of a continent is generally near the coast.
18. Plateaus are high elevations of land which cover large areas. Plateaus of small
area, having level tops, are called table-lands.
59. Plains are low, level surfaces, usually having an extensive area.'
20. The arrangement of these land features with reference to one another, affects not
only the drainage of continents, but also the climate, the commercial industries, and the
productions of the soil. Hence,the surfaces of the continents must be carefully studied.
21. Eastern Hemisphere.-The Eastern Hemisphere extends from Bering Strait, on
the northeast,to Cape Verd,on the southwest. The continents of Europe and Asia form one
united body of land. Africa is naturally a peninsula, joined to Asia.
22. Its chief system of mountains and highlands extends nearly the whole distance
from the northeast to the southwest.
23. From the highest parts of this system, the surface slopes toward the surrounding
waters. The northern slope is gentle; the southern, abrupt.
24. Western Hemisphere.-The Western Hemisphere is composed of two triangular
masses of land joined by an isthmus. It extends nearly north and south, having a slight
inclination toward the northwest.
I By common consent, land surfaces having an elevation exceeding 1,500 or 2,000 feet are called plateaus; those having
a less elevation are plains. 2 Bering, or Behring. The former is now used by the best authorities.
i I
THE LAND SURFACE OF THE EARTH. 23
sft
A Mountain Chain.-Highest peak. -Volcano.-Table land, or plateau.-Lakes at different elevations.-Glacier, ending in a waterfall, which, with
outlet of upper lake, forms the river.
25. the mountain system of the Western Hemisphere extends from Bering Strait
to Cape Horn. On the western side, the slope is abrupt; on the eastern, it is gradual, being
interrupted by low ranges of mountains near the Atlantic ocean.'
26. Asia.-Asia is the largest of the six continents. The Himalaya, together with
several parallel ranges, forms the great mountain system and the main axis of the continent.
Mt. Everest, whose altitude is 29,000 feet, is the highest point.
ff MT.EVEREST E. '" 'TTOr O 3 30 OF' LATrTTTT-Ti.
""I A -I., ^ .-. ";. *.*R-
-I .' P ., P.'
Profile of Asia.
27. The great plateaus of Asia are inclosed by these mountains. Arabia and western
Hindostan are also vast plateaus.
28. The plains of Asia are north of the mountain system. They slope gently toward
the Arctic ocean. There are smaller plains on the borders of the Caspian sea, in the eastern
part of China, and in western Hindostan.
29. Asia is drained by a number of large rivers flowing from the slopes of the moun-
tains into the surrounding waters.
30. The Caspian sea, the sea of Aral, and the basin of the Dead Sea are below the
ocean level.
31. Six large peninsulas on the eastern and the southern side are formed by moun-
tain ranges and plateaus extending into ocean waters.
SIn the capitalization of proper names, the plan followed is the same as that of The American Cyclopedia.
kt-c
24 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
32. Several chains of islands, formed by partly submerged mountain ranges, lie near
the eastern and southeastern shores of the continent.
33. Europe.-Europe joins Asia, the Ural mountains being the natural boundary.
34. The mountain systems of Europe partly inclose the continent. The chief of
these are the Scandinavian, Ural, and Alpine chains, the last system being the principal
system.
... n1N C I IMT.BANC SECTION ACROSS EUROPE MT ELBOORZf .MT. :E. ......
-....... A.\ NCE ,/\ .IT \LY ,\iS-H4 UN. nN R t \ *....
... - ,, -CFAT-A MT -'\ i'
IT W.. U A \! ... P,,,^ V r .L.l A ,. : ._ ^1
Profile of Europe.
35. From this system, the Austrian Alps and the Pindus extend into the Mediterranean
sea. forming the peninsula of Turkey and Greece. The Apennine mountains, in a like manner,
form the peninsula of Italy; and the Scandinavian mountains, the peninsula of Norway and
Sweden.
36. The highest point in the Alps is Mt. Blanc, 15,800 feet high. Mt. Elboorz, in the
Caucasus (cau'ca-sus) mountains, has an altitude of 17,000 feet.
37. The largest plateau is the Spanish or Iberian peninsula. Central and southern
Europe consists almost wholly of plateaus traversed by river valleys.
38. The plains of Europe lie in the northern and northeastern part. The great Russian
plain covers about one-half of Europe. Northern Germany, the Netherlands (Holland),
western France, and a part of Belgium are embraced in this plain.1
39. Europe is drained by a great number of rivers rising in one or another of the
three general elevations. Those of the Russian plain rise in the Valdai Hills or on the slopes
of the Ural mountains. The others rise chiefly in the Alpine mountain system, or else in the
Scandinavian mountains.
40. Africa.-Africa is an immense plateau, taking its shape from the mountains and
the abrupt slopes that form its coast.
41. The chief mountain range is on the eastern side of the continent. The Kong
mountains form the western; and the Atlas mountains, a portion of the northern border.2
."...... SECTION ON THE EQUATORM'T IL"'MA.'"" -,T ...
: ........ ....... 1 -
:E. . .I TL.I. ft r. "' -- __ --- ,',1 C: Q"
T,,..,.,,- -- ----. .- -- -- ......
Profile of Africa.
A portion of Holland lies below the sea level, and is protected from the encroachment of the sea by means of dikes.
S The Crystal, Cameroons, and Mocambe ranges are a continuation of the Kong mountains. The sharp bend of this
mountain chain forms the Gulf of Guinea
THE LAND SURFACE OF THE EARTH. 25
42. The highest points of land are Mts. Kenia, about 20,000 feet, and Kilima Njaro,
about 18,500 feet in height.
43. The southern half of the African plateau has an average elevation of 5,000 feet; the
northern half, about 1,500 feet.
44. Southeast of the center is an elevated basin over 6,000 feet above the sea level.
This basin contains several large lakes, which are the sources of the great river systems
of the continent.1
45. A small portion of the Sahara, south of Tunis, is from 100 to 300 feet below the
sea level.
V46. North America.-North America is an immense plain, bordered on the west and
southwest by the bold and rugged Rocky mountain system, and on the east by the low
parallel ranges which constitute the Appalachian system.
Bird's-eye View, or Relief Map of a part of North America.
47. The Rocky mountains are the main axis of the continent. Parallel to these is a
chain of mountain ranges consisting of the Cascade, the Sierra Nevada, and several shorter
ranges, each having an altitude of about 8,000 feet.
48. The highest points are Mt. St. Elias, 19,500 feet; Mt. Popocatepetl, 18,500 feet; and
Mt. Whitney, 15,086 feet. There are forty peaks, each over 10,000 feet high, in this system.
49. In the eastern part of the continent is the Appalachian system, consisting of sev-
eral low parallel ranges, forming an angle of 450 with the main axis.
50. The great plateaus of North America lie between the parallel ranges of the Rocky
mountain system. The most important of these are the plateau of Mexico and the Great
Basin.
1 The Zambeze, the Livingstone, and the Niger have cut their channels through deep mountain-passes in order to
reach the sea.
26 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
Sierra Nevada Mts. Wasatch Mts. Rocky Mts.
Bird's-eye View of the Great Central Basin.
51. The Great Central Plain lies between these mountain systems. The highest part
of this plain is called the Height of Land. It lies near the northern boundary of the United
States, and forms one of the principal continental watersheds. Although it is traversed by
low ranges of hills, it is neither mountainous nor generally rugged.
52. The Great Lakes, situated
at the summit of the Height of Land, PLATEAU 6000TO8000FTHIGh
constitute the largest body of fresh ,t
water in the world.'
53. The drainage of North Amer- Section of Mexico from the Pacific Ocean to the Gulf of Mexico.
ica is more complete than that of any
other continent, the principal drainage areas being the Arctic slope, the Gulf slope, the Great
Basin, the Atlantic slope, and the Pacific slope.
54. Several remarkable depressions exist in the Pacific Highlands. Death Valley
and the Sink of the Mojave (mo-hah've) river in California, are the principal ones. The
former is about 420, and the latter 350 feet below the sea level.
The summit of the Height of Land may be traced by drawing a line on the map, between the sources of the tribu-
--__
Bird's-eye View of a part of South America.
SThe summit of the Height of Land may be traced by drawing a line on the map, between the sources of the tribu-
taries of the Mississippi and the sources of those rivers whose waters flow into the Arctic ocean. Also draw a line inclosing
the tributaries of the Great Lakes. This will separate the Arctic slope, the Gulf slope, and the valley of th" St. Lawrence
river.
THE LAND SURFACE OF THE EARTH. 27
The Plains. Mississippi R. Ohio Alleghany Mts.
Bird's-eye View of the Mississippi Valley.
55. South America.-South America is triangular in shape, and broadest at the north.
Like North America, it is an immense plain bordered by a high mountain system on the
west and a low one on the east. The Height of Land in the center forms two principal
slopes, one to the north and the other to the south. The crest is so level that the Cas-
siquiare river divides, sending part of its waters to a tributary of the Amazon, and part to
the Orinoco river.
"F 1,000 CHIMBORAZO ... l100-
-18,o000 T .c. VOL. SECTION ON THE EQUATOR i'00
-15,000 ,.l : ; .,T 15,000-
12,000 12,000-
-9,000 r '* "" rl <-' 50
,000 0,000-
__ _'.- T_- -_ .'_.-_ -_".
Profile of South America.
56. The Andes mountains, which are a continuation of the Rocky mountain system,
form the main axis. In the Andes mountains are more than fifteen peaks, each over 16,000
feet high.
57. These mountains extend in two principal ranges, between which are a number of
large plateaus.
58. The Brazilian system of mountains lies on the eastern side of the continent, and
forms an angle of about 45 with the Andean system.
59. The great plains of the Orinoco and the Amazon are in the northern and north-
eastern part. The less extensive pampas of the La Plata are in the southeastern part.
60. Australia.-Australia, in its continental structure, resembles Africa. Its moun-
tains, which are near the coast, slope abruptly to the surrounding waters.
61. The principal mountain system is composed of the Australian Alps, the Blue.
and the Liverpool mountains. This system is in the eastern and southeastern part of the
continent.
62. The great plateau of Australia is in the central part, traversed by low ranges of
mountains. The slope of this plateau is toward the south.
63. The lowland plains are chiefly in the southern and southeastern part. The Gulf
-of Carpentaria is also surrounded by a large, well-drained plain.
64. Several large lakes are in the southern, and a large number of small ones. in the
western part.
28 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
,65. Laws of Structure.-A careful study of the Relief Maps on pages 140-144 show
that the evolution of the Earth's features have been in accordance with definite laws.
66. These are somewhat complex, but they involve the following general principles :
Each continent has high borders and a low center. Its surface, therefore, is basin
shaped.
The greatest length of each continent is in the direction of its principal mountain
system.
The general shape of each continent is that of a triangle.
The highest mountains border the largest oceans.
SThe greatest elevations of land are in the Torrid zone.
67. It must also be kept in mind that the continents were not always where they are
now, nor did they always have the shape they now have. Whatever changes in position,
level, or outline may have taken place, the laws of structure have remained unaltered.
WHAT HAS BEEN TAUGHT IN CHAPTER III.
S The Earth's surface comprises about 144,- axis is the Alpine system of mountains, from
000,000 square miles of water and 53,000,000 whose summit it slopes gently to the north and
of land. Of the latter 3,000,000 are islands, abruptly to the south.
The land surface consists of triangular shaped Africa is an immense plateau rising abruptly
continents, extending from the north toward out of the sea. Its main axis is on the eastern
the south, side. Its surface is drained chiefly by the Nile,
Three of the continents are, for the greater Zambeze, and Congo or Livingstone rivers.
part, in the North Temperate zone, and three North America consists of a great plain bor-
mostly in the Torrid zone. dered on the east and the west by mountain
The land masses lying on opposite sides of the chains. Of these, the Rocky mountain system is
Earth are known as the Eastern Continent and the most extensive. It occupies the western part
the Western Continent. Their divisions are also of the continent.
called continents. The great continental plain extends from the
The northern group of continents is bounded Arctic ocean to the Gulf of Mexico. Its drain-
by very irregular coasts, and is noted for the age in the southern part is effected by the Missis-
great number of indentations. sippi river system.
The Eastern Continent extends from north- The Appalachian mountain system comprises
east to southwest, having a length of about 10,000 several parallel ranges lying near the eastern
miles. Its main axis is the Himalaya mountain border.
system. South America resembles North America in its
The Western Continent consists of two tri- continental structure, consisting of a great plain
angles of land, extending from north to south bordered by parallel mountain ranges.
about 11,000 miles. Its main axris is the Rocky The Andes, a continuation of the Rocky moun-
nmontaain system. tains, forms the main axis.
Asia is the largest continent. Its highest point The great continental lowlands extend from
is Mt. Everest. From the great plateau of the the north to south.
limualaya mountains,the surface slopes in every The Amazon, Orinoco, and La Plata rivers
direction toward the surrounding oceans. The constitute the chief drainage systems.
Dead and Caspian seas are below the ocean level. Australia also resembles the American conti-
Europe, in proportion to its size, has a larger nents, consisting of a low plain bordered by
coast line than any other continent. Its main mountains on the east and the west.
MOUNTAINS, PLATEAUS, AND PLAINS. 29
C IAPTER IV.
MOUNTAINS, PLATEAUS, AND PL AIN S.
1. Mountain Structure.-It
is now believed that mountains
have been formed by a shrinking
of the Earth's crust, owing to its
gradual cooling. z
2. The shrinkage being
greatest in the interior, the over-
lying strata are crushed together
sideways.
3. Such side pressure, it is
evident, forms immense wrinkles
hundreds of miles wide, and often Section of Uintah Mts. A, Green River Cation; BB and CC, Strata worn by water;
many thousand miles long DD, Mining Shafts. The dotted lines show the original fold.
many thousand miles long.1
4. The simplest mountain range is one consisting of a single fold or wrinkle.
The Uintah range of Utah is an example of this kind of mountain formation.
5. Oftener, a range consists of several gentle folds, as in the case of the Jura moun-
tains.
6. But most frequently, the strata, instead of occurring in gentle folds, are pressed
closely together. This kind of mountain structure is finely illustrated by the Coast Range
of California and the Appalachian system of the Atlantic coast.
7. Mountain Chains.
--Mountain chains are al-
A ways composed of sediment-
A A ary or stratified rock.2
8. It is a remarkable
fact also, that the strata
Which are found in a moun-
-B B
tain chain are much thicker
Section of Coast Range near Santa Cruz, Cal. The folded strata at the surface have been worn away. tn he ae straa Occ
AA, Strata; BB, Granite Axis. than the same strata occur-
ring elsewhere.3
9. Mode of Formation.-Mountain systems, therefore, seem to be directly connected
with thick accumulations of sediment.
10. These great accumulations always occur along the shores of continents, where
everything washed from the surface of the land is finally deposited by the agency of rivers,
winds, waves, and tides.
SThere is evidence, also, that in many instances the crust of the Earth has been rent, and that either igneous or meta-
morphic rock has been forced upward through the fissure thus formed.
8 In many instances igneous rock has been thrust upward to the surface.
"a "The strata composing the Appalachian system are 40,000 feet thick, while the same strata on the Mississippi river
are only 4,000 feet."-Le Conte.
.
30 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
The Bad Lands of Dakota.-Water Sculptured Mountains.
11. We are thus led to believe that mountain chains are formed by the wrinkling or
crumpling of the Earth's crust along those sea shores on which accumulations of sediment
have been deposited.1
12. That mountains have once been sea bottoms is shown by the following facts:-
First. They are composed of aqueous (d'-que-us) rocks.
Second. The fossils found within their strata represent chiefly those types of life that
have inhabited the sea only.
Third. In several instances, strata of sea shells in their natural state, mixed with sea
sand, are found in mountain ranges at an elevation of many feet above the sea.2
13. Laws of Position.-By closely studying the relief maps, the pupil will observe
certain general laws concerning mountain structure.
First. The highest mountain peaks occur in the largest continents.
Second. The most extensive systems are found in the largest continents.
Third. The average height of mountains is least toward the poles and greatest toward
the equator.
14. Continental Axes.-The chief systems of a continent may be considered its skeleton,
inasmuch as they give to the continent its general shape and extent. They are, therefore,
called the axes of the continent.
It is also certain that parallel ranges of a system have been formed successively, and also successively coastward."
-Dana.
I Such deposits occur at San Pedro, California. The highest stratum is about four feet below the surface, and is over-
laid by sandstone. Other strata are found, at irregular intervals, below the one mentioned.
__cnd ,h .;sil ---n "ihi .--i ::'- --r-a --:( re r s n -= i fl _=--,_- o-----_ _.---------.c ? 5._:.
-av -__:_te _'_---_ __-?T o' ,n2 -'-- ---- y:: -
MO UNVTAINS, PL'.4 TA US, AND PLAINS. 31
AUSTR'LIA. EUROPE. SOUTH AMERICA. NORTH AMERICA. AFRICA. ASIA.
S31 H 3 J I 4
The Relative Proportion of Highlands and Lowlands.-Highlands shaded, the Lowlands white.
15. The Rocky antd Appalachian systems, embracing the Great Central Plain be-
tween their crests, form the general outline of North America.
16. The Andean and Brazilian systems constitute a frame upon which South America
is modeled; having, like North America, mountain borders, between whiclr lies the great
continental plain.
17. Europe and Asia are each traversed from northeast to southwest, by irregular and
complex systems. From the great, central backbone of each, numerous spurs project, forming
the numerous peninsulas for which these continents are noted.
18. Africa and Australia resemble each other in their mountain systems, which form
a rim surrounding a comparatively low interior.
19. The importance of mountains cannot be too greatly estimated. On their presence
and position, the rainfall, drainage, and climate of a country almost entirely depend.
20. The most extensive mountain system in the world is the Rocky and Andean,
which has a total length of nearly 11,000 miles, reaching from Alaska to Patagonia. In the
western part of the United States, there are about 50 parallel ranges in this system.
21. The highest mountain peak in the world is Mt. Everest, situated in the Hima-
laya range. Mt. Everest is over 29,000 feet, or nearly 53 miles high.
22. Plateaus.-The highlands of the Earth are not always mountains; often, they con-
sist of vast upland plains, called plateaus. These are usually situated between those mountain
ranges which form the margins of a mountain system.
23. Thus, the Great Basin lies between the Rocky and the Sierra Nevada mountains.
The plateau of Thibet is situated between the Himalaya and the Kuen Lun range. The
plateau of Bolivia lies between the two main ranges of the Andes.'
24. The surface of a plateau is not necessarily level; on the contrary, it is often rugged
and mountainous. The Andes mountains rest on a high plateau. The Great Basin is covered
"with a network of mountains and valleys.
25. About one-half of the Earth's land-surface consists of plateaus and highlands.
Generally,they are infertile and ill-adapted to habitation. They contain, however, nearly all
the mineral wealth of the world. Their proportion is approximately shown in the diagram.
i Other plateaus, as the Mexican, rise from the sea level in terraces, or else by a gradual and gentle slope, like the
"Plains" of North America. The Plains rise imperceptibly from the Mississippi river to the foot hills of the Rocky moun-
tains, where their altitude is about 5,000 feet.
32 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
26. The principal plateaus of the Western Hemisphere are those of the Western High-
lands and Mexico, in North America, and the plateaus of Bolivia and Titicaca, in South
America.
27. The plateaus of the Eastern Hemisphere are noted for their great size and elevation.
28. Afiica is an immense plateau,having an elevation varying from 2,500 to 8,000 feet.1
29. Asia contains the most notable plateaus of the world, both as regards size and
elevation. The most prominent are the plateaus of Thibet, Gobi, Persia, and Arabia.
30. The chief plateaus of Europe are the Austrian plateau and the Spanish
peninsula.
31. Australia is skirted on the eastern and the western border by low plateaus having
an average altitude of 2,000 feet.
The following table shows the most notable plateaus of the world :
NAME F PATEAU. AREA IN AVERAGE ELEVATION,
NAME O PLATEAUS. SQUARE MILES. IN FEET.
Africa (without lowlands) .......... 9,500,000 3,000 to 6,000
Arabia ................................. 700,000 4,000 to 5,000
Gobi.............. ................. .. 400,000 4,500 to 5,500
Persia................. ............. 300,000 3,000 to 4,000
Spanish Peninsula.................... 225,000 2,500 to 4,000
Mexican............. ............. 180,000 6,000 to 8,000
Thibet ................... ......... 160,000 11,000 to 12.500
Bolivia ............... .. .............. 120,000 10,000 to 13,000
Great Basin ........................ 120,000 4,500 to 6,000
32. Plains.-Plains and lowlands form the remaining half of the land-surface. They
are large tracts, usually of level country, having an elevation of not more than 1,000 feet.
33. There are two great classes of plains, differing both in origin and general features.
34. Alluvial Plains.-Alluvial plains owe their origin to rivers whose waters carry
material from the mountains and deposit it in places where the current runs less swiftly.
This occurs chiefly at the mouths of rivers and along their lower courses. Alluvial plains
are always level.
35. The plains of the Amazon, the Orinoco, the La Plata. and also those of China and
Hindostan, are examples of this class. Much of the Mississippi valley has also been formed
in a similar manner.
36. Marine Plains.-Marine plains are old sea bottoms which have been gradually
lifted above the sea level.
37. The plains surrounding the Caspian and Baltic seas, the northern part of the
Mississippi valley, and especially those which border large oceans, are examples of marine
plains.
I Sahara, in the northern part of Africa, has an average altitude of 1,500 feet.
MOUNTAINS, PLATEAUS, AND PLAINS. 33
38. Marine plains,
especially those of
5_ _recent formation,
S are often sandy and
Sterile. Their soils
ST p- : o N generally contain
Large quantities of
salt, soda, and pot-
ash.'
39. The Steppes
of Russia and Si-
beria are marine
plains, but they have
Seen, in many places,
Covered with sedi--
ment brought down
Tby the rivers flowing
o-netSi through them.
As the altitude in-
Screases, t he plain.
43.-- .e .- of generally becomes.
Silly. Such is the
case with the Sibe-
The Steppes or Plains of Siberia, looking south toward the Altai mountains. rian and the North
American plains.
40. The plains of North America lie between its two mountain systems. In the
higher portions, they are covered with forests of valuable timber; but toward the north, they
become a dreary, frozen waste.
41. Much of the southern portion is a vast cypress swamp whose surface is scarcely
above the sea level.2
42. The central and southern portions of the plains of North America supply nearly
one-third of the wheat and corn, and about one-half of the cotton, used in the civilized world.
The level plains of North America east of the Mississippi are called prairies; those west of
the Mississippi, "the plains."
43. The plains of South America also lie between the continental mountain systems..
Those of the Orinoco are alluvial. They are called llafios (lyah'-noce). For a few months,
they dry and parch under the scorching rays of a tropical sun, until they resemble a desert.
44. Then, the rainy season sets in; the streams overflow their banks; and, save here
and there a projecting knoll, the whole country, as far as the eye can reach, is under water.a
SThe plain which constitutes the southwestern part of California is a remarkable example of recent, marine Flain.
Layers of sea shells in a perfect state of preservation are frequently found at a distance of but a few feet from the surface.
The unpetrified skeletons of whales are found in large numbers, some at an altitude of several hundred feet above the sea
level
"These cypress swamps are called everglades. The great Dismal Swamp of Virginia is a notable example.
Just before the wet season begins, the herds of cattle and horses stampede; and in due time, reach the foothills of
the plateaus. The few that lag behind, usually perish. It is not an uncommon sight to see a small hillock which projects
above the surface of the water, crowded with wild animals of every species, struggling with one another to keep a foothold
above the water. Alligators and other reptiles that have remained dormant during the drought, appear in great numbers.
34 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
45. The plains of the Amazon are covered with forests, so dense and impenetrable,
that the streams of water flowing through them are often the only highways. These plains
are called selvas. From them are obtained a great variety of ornamental and dye woods.
The India rubber tree (Siphonia elastica) is abundant.'
46. The plains of the La Plata, called pampas, have an extent of about 175,000 square
miles. They are well drained, and afford pasturage to immense herds of cattle, which out-
number those in all other parts of the world together. Millions are slaughtered annually
for their hides, horns, and beef. Neither the rainy nor the dry season is severe. Hence, the
pampas are the most valuable part of the continent, in respect to their natural resources.
'47. The three plains of South America are not separated by any distinct, physical
features.
48. The northern parts of Europe and Asia constitute an immense plain bordering
the Arctic ocean. The three divisions of this plain comprise the forests of the south, the
agricultural lands of the middle, and the tundras of the northern part.
49. The Ural mountains, crossing this plain at right angles to its line of greatest length,
form a ridge corresponding to the Height of Land of the American plains.
50. The higher portions of this plain are the steppes (steps). That part bordering the
Arctic ocean is generally known as the tundras (toon-drahs).
51. In summer, the tundras are swamps in which nothing but the lowest forms of
vegetable life, such as mosses and lichens, can exist. In winter,they are frozen wastes.2
52. Africa contains no extensive plains. There are lowlands bordering the ocean, a
number of alluvial plains along the larger rivers, and parts of the Sahara; but there are no
such plains as characterize the other continents.
53. Of the river valleys, that of the Nile is the most important. This valley, owing to
the annual overflow of the Nile, is exceedingly fertile, and produces valuable crops of grain.3
Each flood deposits a fresh layer of soil on the surface of the valley. Were it not for this
overflow,the valley of the Nile would be sterile and uninhabitable.
54. The oases of the Great Desert are remarkable for their perpetual fertility. They
are well supplied with water all the year, and in consequence, present a strong contrast to
the surrounding desert.
55. In structure, the oases are depressions in the limestone formation. A stratum of
clay and sand forms the bottom of the basin, holding the water that finds its way from the
surrounding highlands.4
1 The only inhabitants, except the traders who live along the navigable rivers, are savages of the lowest type of
humanity.
2 The cause of these conditions is remarkable and interesting. The mouths of the rivers flowing into the Arctic
ocean are in high latitude, and hence are frozen during a great part of the year. The rivers having no open channel, over-
flow their banks and convert the whole country into a vast morass. It was in the tundras of the Lena river that Lieut. De
Long and his party. of the ill-fated Jeannette, perished.
In their general features, the Arctic plains of the Eastern Hemisphere do not differ-from the North American plains in
the same latitude.
3 The rising of the river begins in June and continues until the middle of September, when it begins to subside. The
water, at the highest stage,is sometimes 80 feet above low water level.
There are about 80 oases, of which 20 are inhabited. The largest, Ammonium, contains several towns, and has an
area of 3,000 to 4,000 square miles. The oases are stopping-places for caravans, where they obtain supplies of food and
water.
MOUNTAINS, PLATEACTUS, AND PLAINS. 35
56. The lowlands of Australia are the alluvial valleys of the Murray river and its
tributaries. These valleys are extremely fertile and are productive of great wealth.
57. The great plains of Australia, however, lie in the interior of the continent. During
the rainy season, they are more or less productive, but in the summer they soon become
parched and desolate.
58. There are also large, sandy plains containing salt lakes, but destitute of all vegeta-
tion, save a long, stiff grass, called spinifex. Swampy lands are occasionally found in these
plains. Owing to the great heat and the lack of water, the central Australian plains are
uninhabitable.'
WHAT HAS BEEN TAUGHT IN CHAPTER IV.
That 'mountains have been formed by the Their surfaces are not always level, being
crust of the Earth shrinking. upon a contract- frequently rugged, and often studded with moun-
ing interior, thus producing immense folds, or tain peaks and short mountain ranges.
wrinkles. Plains are formed either by the deposition
The wrinkles or mountains thus formed are of sediment along the course of a river, or by
made by side crushing, and frequently igneous the elevation of sea bottoms.
rock is thrust upward through rents found in, Many marine plains have been subsequently
the broken, strata, shaped by rivers. Recent marine plains have
Sometimes the mountain chain consists of a usually a sandy soil and are frequently ster-
single fold or plication, but oftener, of several ile.
folds crushed together. The chief plain, of North lAmerica extends
Mountain chains are composed of enormous from the Arctic ocean on the north to the Gulf
thicknesses of sedimentary rock. of Mexico on the south.
"The mountain systems of a continent form the The principal plain, of South America extends
skeleton,which gives the continent its outline. from the moouth of the Orinoco to the mouth of
The ranges composing a mountain system are La Plata river, being drained by the Amazon,
generally parallel to one another. Orinoco, and La Plata rivers.
The chief 'mountain systems of the Westerni The largest plains of Europe and Asia border
Hemisphere extend nearly north and south, the Arctic ocean, and rise from the sea in suc-
Those of the Eastern Ilemitsphere e. teend from cessive terraces.
the northeast to the soutth rest. The plains of southern Asia are chiefly
Plateaus are elevated surfaces which usually alluvial, and constitute the most thickly inhab-
extend between parallel mountain ranges, ited part of the continent.
The chief plateaus of the Western Hemtisphere The oases of the Great Desert, the most re-
are the western Highlanids anld Mexican pla- markable of African plains, tare depressions
teau of .North _America, (lidt the iBolivian and surrounded by limestone formation, and under-
Andean plateaus of South America. laid u'ith a stratum of clay.
Those of the Eastern Hemisphere are Arabia, The plains of Australia are in the interior
Gobi, Persia, and Thibet; the latter being the of the continent. The!/ are generally destitute of
highest plateau in the world, vegetation and are subject to excessive drough.t.
SThe average daily temperature frequently exceeds 1100 F. Howlitt, an explorer, states that lie has recorded a tem-
perature of 1890 F.
36 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
CHAPTER V.
ISLAND D S.
1. Area and Classification.-About 3,000,000 square miles, or nearly one-seventeenth
of the land surface of the Earth, consists of islands.
2. These, with respect to their structure and position, are either continental or oceanic.
3. Continental Islands.-Continental islands are generally elongated in shape, and
are parallel to the coasts near which they lie. In structure, they are usually like the neigh-
boring continents.
4. Comparing their strata with those of the adjacent continent, we find not only similar
species of living plants and animals, but also the same kind of fossils.
5. From this evidence, continental islands are believed to be partly submerged mountain
chains, belonging to the continent to which they are adjacent.
6. On any map of the Western Hemisphere, trace a continuous line from Yucatan,
through the West Indies and the Lesser Antilles (ahn-teel'), to the mouth of the Orinoco
river. This chain of islands is a spur of the Rocky mountain system.
7. On a map of the Eastern Hemisphere, also trace a line from Kamtschatka, through
the Kurile islands, the Japan Empire, the Liukiu and Philippine (fil'ip-pin) islands. This is
a mountain range,lying parallel to the eastern shores of Asia.
8. Sumatra, Java, and the chain lying to the eastward, form a mountain range parallel
to the one which constitutes the peninsula of Malacca.
9. This range may be traced northward to the divide between the Irrawaddy and the
Ganges river.
10. From the western extremity of the Aliaskan peninsula, a chain of islands extends
nearly to Asia.. This chain belongs to the Rocky mountain system.
11. The chains of islands just described are both mountainous and volcanic. In fact,
they contain nineteen-twentieths of the volcanoes in the world. In more than one instance,
every island of the chain is a volcanic cone.
12. There is one group of continental islands which is neither mountainous nor
volcanic. It comprises the islands of the Arctic archipelago.'
13. These islands form a partly submerged marine plain, which seems to be a continua-
tion of the Arctic plain of North America. Although not mountainous, their surface is
rugged, and, in many instances, "reefs of rock rising abruptly out of the sea, form their
natural boundaries."
1 Greenland, Cumberland, and Banks islands, together with the archipelago lying northeast of North America, consti-
tute the exception mentioned. Comparatively little is known about this group of islands. Baron NordenskjOld, who
penetrated Greenland to a distance of 100 miles, found the interior a barren plateau, covered with ice and snow. According
to his opinion, Greenland consists of a number of islands joined by a perpetual bond of ice.
ISLANDS. 37
14. Oceanic Islands.-Nearly all of the oceanic islands are in the Pacific ocean, at
a considerable distance from any continent. These groups constitute the divisions of Poly-
nesia and Micronesia.
15. Oceanic islands differ from continental islands in structure; for while the former
are similar to the main land near by, the latter are formed either of volcanic ejections, or of
limestone.
16. The islands formed of volcanic ejections are
usually active volcanoes having a considerable alti-
tude; those composed of limestone are the low tops
of coral (k6r'dl) reefs, and are called coral islands.
17. Coral Islands.-Coral islands are, in many
respects, the most interesting features in the world.
Each island is an irregular ring of land, usually
broken in several places, and having a surface only
a few feet above the sea level.
18. The island forming this ring is called an
atoll (a-t61'); the lake inclosed by the atoll, a lagoon X.-- .
(la-goon').
19. Within the lagoon the water is shallow,
never exceeding forty or fifty fathoms in depth.
Outside the lagoon it is unfathomable at a short coral Reef and Lagoon.
distance from the shore.
20. The atoll is nearly always covered with a luxuriant growth of vegetation, limited
however, to a very few species.'
21. Structure.-In many instances, a volcanic mountain occupies the center of the
lagoon: This fact is an important one, because it tells the wonderful story of the building
of the island.
22. The reefs composing the island are limestone, and the limestone has been taken
by the coral polyp, atom by atom, out of the water to make its skeleton.
23. The Coral Polyp.-The coral
G B Q s polyp is a zo6ph yte, a form of animal life
.. -_ ~ which may be likened to a tree, with
*-__ its trunk and multitude of branches.
S_ The mouths of the coral polyp corn-
""C pletely cover its upper surface, closely
AA, Section ofreef; B, Lagoon; 0, Volcanic Mountain, D D, Ocean Waters. resembling the petals of flowers, which
Section of a Coral Island. they rival, both in color and beauty.
24. In a single community the growth of the coral is chiefly upward; but when multi-
tudes of such communities live side by side, their branches interlock, and finally form one
compact mass.
SThere are seldom more than forty or fifty species,-often not more than half that number. These consist of the-
Cocoa and date palms, the bread-fruit tree, the banana, and a number of less important kinds.
"38 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
W.
Vegetation of a Coral Island in Polynesia.
25. Thus, in time, the fringe of coral becomes a solid ring-like wall, completely encircling
the island on whose shores the seemingly insignificant animal-flower was cast.
26. Coral polyps sometimes multiply by eggs, or egg-germs, and these are distributed
along the shore by winds and waves. They multiply chiefly, however, by the process of bud-
ding and branching just described.
27. Although the coral polyps cannot live more than 120 feet below the surface of the
water, yet the reefs they have built extend thousands of feet in depth. How, then, did the
polyp reach these depths ? We shall see.
28. Formation of the Island.-The researches of Darwin have led to the discovery
that the islands and volcanic cones, along whose shores the coral polyps built, have been
gradually sinking.
29. As, little by little, these islands sunk, the coral built upwards, always keeping near
to the surface of the water, but never building above it. In time, the waves lashing the crests
of the reefs, broke off masses and piled them up, just as now the storm waves sometimes
throw up bars of sand and gravel on our coasts.
30. Waves and migrating birds scattered over the island the seeds brought from other
lands. In the course of years, these covered the island with a mantle of verdure.
31. Sometimes, the volcanic mountain reaches a great elevation; often, its summit is
scarcely above the water level, while in other instances, it is entirely below the surface, and
covered with coral growths.
32. Apparently the Polynesian and Micronesian groups of islands consist of an immense
plateau about 6,000 miles long and 2,000 miles wide, almost wholly submerged.
ISLAND S. 39
33. Examine a map of Oceanica and you will not fail to notice that the islands com-
posing each group are in regular lines, just such lines as would appear above the surface
of the ocean, if the plateau of Thibet, for instance, were submerged till only the highest
.crests were out of water.
34. Fringing Reefs.-Another kind of coral architecture, namely, the reefs which
.often skirt the shores of continents, possesses more than ordinary interest. They seldom
exceed half a dozen miles in width, while they are sometimes many hundred miles long.
35. The West Indies and the Bermuda islands are fringed with these reefs. The
peninsula of Florida owes its shape chiefly to them. On the northeastern shores of Australia,
the coral reef exceeds 1,250 miles in length.1
36. Wave-formed Islands.-The rivers of the Atlantic slope of the United States are
constantly depositing their sediment all along its eastern shores. But while the river cur-
rents tend to carry it seaward, the waves and wind push it landward.
37. Consequently, between the two opposing forces, a long reef or sand-spit is thrown
up along the shore and parallel to it. The sand-spits opposite Hatteras inlet are fine
examples of wave-formed islands.
WHAT HAS BEEN TAUGHT IN CHAPTER V.
Islands, constituting about one-seventeenth of The various islands composing the groups are
the land surface of the Earth, have oan aggre- usually ranged in parallel lines.
Vgate area of 3,000,000 square miles. Oceanic islands consist either of volcanic cones,
Continental islands always lie near and par- or else reefs of coral limestone.
tallel to the continents of which, in structure, they The coral island is usually a ring-shaped reef
form a part. inclosing a shallow lagoon, in the center of which
Neither the rocks that compose continental there is a volcanic mountain.
islands, nor the forms of life upon them, difer Each atoll is the work of the coral polyp,
from those of the continents near which they lie. which, building in shallow water, surrounded
They constitute partly submerged mountain the island with a reef of coral limestone.
chains and plateaus. TlWhile the island slocly sank, the coral polyp
Nearly all continental islands are volcanic, built (s rapidly towards the surface.
and they contain nineteen-t-tentieths of the rol- MIany continental shores are fringed with
*canoes of the globe. coral reefs, formed in much the same mian-
Oceanic islands are always at a great dis- ner as the coral islands.
stance from any large body of land, nearly all The vegetation of coral islands is limited to
of them being in the Pacific ocean, a few species of palms.
"In the tropical Pacific every high island or previously existing land is surrounded by a reef which attaches itself to
the shore line and extends outward on every side just beneath the water level, as far as the condition of depth will allow,
forming a submarine platform bordering the island or other land."
In many cases, besides the fringing reef there is another reef surrounding the island like a submarine rampart, at
"the distance of from ten to fifty miles. As the reef rises nearly to the surface of the sea, its position is inilh:a;,:. by a snowy
!girdle of breakers surrounding the island, and the snowy girdle is gemmed with wave formed green islands. Within this
.girdle, and between the rampart and the island, there is a ship canal twenty or thirty fathoms deep. Through breaks in the
'coral rampart, ships enter this channel, and find secure harbor in a stormy sea "-Le Conte.
Circular reefs or atolls have already been described. Ecery circular reef marks the locality of a sunken island.
40 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
CHAPTER VI.
MAGN-ETISM.
V
L ,' ,' I -
"i :' ..- i
-..... 'N 0 '" is 'I ..... .1 ', .1 t A ,, "
I N- r, '-, .! i.-i L '_l .' -- ',. -. ~' -- "T I- ~ I
i .I -'. E," \ .I -,'--.. i -- ]- ,-, 1 '
"I ; .
I j I
Compiled from the U. S. and the Br. Reports, by J. W. Redway.
1. Properties.-A magnet is usually a bar of steel which has the property of drawing-
towards itself pieces of iron or nickel. When balanced and suspended by a string, the mag-
net comes to rest,pointing in an unvarying direction.
2. The word magnet is derived from Magnesia, a city of Asia Minor, near which lode-
stone, a kind of iron ore having magnetic properties, was originally found.
3. An artificial magnet is usually a piece of steel which has been magnetized by elec-
tricity, or by rubbing its ends with another magnet. Steel or nickel must be used, because
these metals retain their magnetism permanently, while soft iron does not.
4. If iron filings are sprinkled on a piece of paper under which a bar magnet lies, they
will cluster in curved lines about the ends of the bar, while few or none of the filings adhere
to the center, showing that magnetism appears to be strongest at the ends of the bar.
5. Polarity.-The two ends of the bar, at which the magnetism is strongest, are the
poles of the magnet. For convenience, they are called the north-seeking or -, and the
south-seeking or + poles.
6. The like poles of two magnets repel, the unlike poles attract each other. Either
pole attracts bits of unmagnetized iron and nickel.
7. If a small piece of steel, as half a knitting-needle, be suspended by a strand of silk.
and exactly balanced, it will rest indifferently in any position to which it may be pointed.
MA GNE TI' S M. 41
8. But if the ends of the needle be rubbed,
one by the marked, the other by the unmarked -
-end of a magnet, the needle no longer remains
indifferent to its position : it turns until it points
nearly or quite north and south.
9. No matter how carefully you may change
its position, the needle will swing back until it
regains its fixed direction.
10. It does not even remain in balance, ,,
for, as soon as the needle is magnetized, the
north-seeking end (north of the equator) turns
downward or "dips."
11. The Compass.-A compass consists of
a small magnet, called a needle, so poised on a Iron filings strewn upon a sheet of paper held over a Magnet.
pivot that it turns freely. In the mariner's com-
pass the needle is fastened to a circular card, on whose circumference the names of the
cardinal points and their subdivisions are printed. Both needle and card turn on the pivot.'
12. No matter in what part of the world the compass may be-on sea or on land-the
needle always seeks its north-and-south position.
13. This wonderful property of the compass-needle makes it of priceless value to the
sailor; as without it, the navigation of the ocean would almost be an impossibility.
14. Magnetic Variation.-But the compass-needle does not always point exactly north
and south. In fact, there are but very few places on the Earth where it does, and these
places are constantly changing.
15. Look on the map at the beginning of this chapter and find the line marked 0. In
1880, everywhere along this line the compass-
needle pointed due north and south. This line
is called the line of no declination.
t 16. In all places east of this line, the
north-seeking end of the needle turns a little
towards the west : in all places west of the line
it is deflected eastward. The figures at the end
of each line tell how many degrees, east or
west, the direction of the needle varies from
the true meridian.
17. Magnetic Poles.-These lines ap-
-----proach towards the north, and finally intersect
in the western part of Boothia Land. The point
S of intersection is the magnetic North Pole."
---- 18. Magnetic Dip.-- At the magnetic
The Compass. North Pole, a needle suspended as you see in the
The compass box is so mounted that it always remains level. The box is sometimes filled with a liquid on which
the card and needle almost float,-only a very slight weight resting on the pivot.
The latitude of the magnetic North Pole is 700 8' N.; its longitude is 96' 45' W. This position has been determined
,bY actual observation. The exact locality of the magnetic South Pole is only theoretically known.
k:
42 MONTEITH'S NEW PHYSICAL GEOGRAPHY
cut, has a vertical position, the north-seeking or end being down. Going southward, how-
ever, it gradually recovers its position, until, at a point near the equator it ceases to dip
and its position is horizontal.
19. Going still farther southward, the south-
At Magnetice At Magnetic At Magnetic
S. Pole. Equator. Ple seeking or + pole now dips. The dip constantly
"increases till the south magnetic pole is reached,
+ where the needle's position is again vertical; this
time the south-seeking pole is downward.'
20. The Earth's Directive Force.-Thus we
see that the Earth itself has all the properties of a
magnet. Like a magnet it has two magnetic poles,
Position of the needle at different parts of the Earth. and these affect the compass-needle in just the
same manner as does any other magnet.
21. Change in Variation.-We must keep in mind that not only is the compass vari-
ation constantly changing, but also that the rate of change is seldom alike in any two places
distant from each other, and is itself constantly changing. In fact, there are no factors or
values pertaining to magnetism that are not subject to frequent and unexpected changes.2
22. Periodic Variations.-There is another series of magnetic variations having great
interest, because they are governed by forces beyond the influence of the Earth. These are
the daily, the monthly, the yearly variations, and the period of magnetic storms.
23. The first three of these, though very slight, are regular in occurrence, and toler-
ably uniform. It is thought that they are due to the influence of the sun and the moon.
They are vibrations of the needle rather than permanent variations.
24. Magnetic Storms.-About every eleven years the magnetic needle is subject to
violent disturbances which are closely connected with sun-spots. These disturbances are
called "magnetic storms."
25. Whenever a sun-spot shows signs of agitation or rapid change, a powerful effect
upon the magnetic needle is noticeable. Quiet sun-spots, on the contrary, have little or no
effect.
26. During a magnetic storm, the needle trembles constantly and swings on its pivot
over an arc measuring sometimes one or two degrees. The Aurora Borealis is often visible
at the time of a severe storm, and telegraph lines frequently refuse to work.
27. Thus we see that the magnetic needle never rests, but forever swings back and
forth, controlled by a force we know not. Fortunately for those who use the compass, these
changes are always slight-sometimes almost imperceptible-yet they nevertheless exist.
2 Ship compasses are so constructed that the needle and card are always horizontal. In the Arctic regions,the vertical
force is so strong, and the horizontal force so weak, that the compass-needle will scarcely turn on the pivot. On whaling
vessels, the helmsman frequently attaches a cord to the compass-box, giving the latter an occasional shake, in order that the
needle may settle in some definite direction.
2 The following table shows the changes in variation at Paris during the last 300 years:
Variation in 1580, 11 20' E. Variation in 1700, 80 10' W. Variation in 1816, 22 25' W. IVariation in 1829, 22 12' W.
"1618, 8 0' E. 1780, 19" 551 W. 1823, 22" 23' W. 1835, 22 4' W.
"1663, 0 0' 1814, 22" 34' W. 1828,22 5' W. 1854, 22 10' W.
In some parts of the United States, the annual change is 71' (angular measure). In New Mexico and Arizona, there
has been no change for several years. The yearly increase is greater toward the northern part of the continent. On the
Pacific coast, the easterly variation is increasing; on the Atlantic coast and the Mississippi valley, the westerly variation is
increasing.- U. 8. Coast Survey-Report for 1883.
It is evident that the map used to illustrate this chapter will be useless ten years hence.
MA G NETISM. 43
28. What magnetism is and why it so mysteriously controls the piece of steel in
which it resides, are questions that cannot be answered. We know a few of the phenomena
only, and there our knowledge ceases.
29. It is thought by many of the best observers and students of magnetism, that the
magnetic poles are moving in irregular'paths about the geographical poles. This theory is
not yet fully confirmed.
30. In several countries,magnetic observatories have been established, under the control
of their respective governments, for the purpose of investigating the phenomena, and
studying the laws of magnetism.1
WHAT HAS BEEN TAUGHT IN CHAPTER VI.
Magnets are pieces of steel or nickel having West of this line, the end of the needle points
the property of attracting other pieces of steel east of north. East of it, the end of the needle
and nickel or bits of soft iron. points west of north.
Steel and nickel retain their magnetism per- At the magnetic North Pole, the needle takes
nanently, while iron does not. a vertical position, the end down.
A piece of steel accurately balanced, and then At the magnetic South Pole, the needle is also
magnetized, rests always in a north-and-south vertical, the + end down.
position. Midway between the magnetic poles,the needle
It no longer remains balanced, one end of the lies horizontal.
needle dipping toward the Earth. These variations are themselves constantly
The end of the needle pointing towards the changing.
north is called the north or pole; the other, the The rate of change is not uniform.
south or + pole. In every place, the magnetic needle has three,
A mariner's compass consists of a magnet regular variations-the daily, the monthly, and'
balanced and fastened to a card, on which the the yearly.
cardinal points are printed. About every eleven years, there occurs a period,
The compass-needle never points exactly north during which the magnetic needle is subject to
and south except on a certain irregular line unusual disturbances.
called the magnetic meridian, or line of no During this period of magnetic storms, the
declination. Aurora Borealis is of frequent occurrence.
The United States Magnetic Observatory is located at Los Angeles, California. It is a low frame building, partly
underground. The walls, each a foot in thickness, are double, and have a space of three feet between them. In the erection
of this building no iron has been used-copper being employed for all metal work.
In the magnet room are three magnets, on which observations are taken. The first of these, suspended by a strand
of unspun silk, is called the unifilar magnetometer. This instrument records variations in declination only. The second, or
bifilar magnetometer, is suspended by two strands in such a manner that it is forced to point east and west. It is employed to
measure the strength of the magnetic force. When this force increases, the magnet turns toward the geographical meridian.
The third magnet, called the vertical force or balance magnetometer, is balanced on a knife edge, and is used to detect any
change of dip or vertical force. All of these instruments rest on solid piers of masonry and each is covered by a glass globe,
in order to guard it from possible disturbance.
To each magnet,a mirror is attached, before which a lamp is placed in such a manner that the mirror reflects a small
dot of light upon a cylinder covered with photographic paper. Now, if the magnet turns ever so little, the dot of light
moves, and its motion is recorded on the photographic paper. Each cylinder revolves once in twenty-four hours, and therefore
the swerving ray of light has photographed an irregular line the whole length of the paper. The amount of deviation of
this irregular line shows the variation for every minute of the day. Each magnet is provided with a telescope and scale..
in order that readings may be made independently of the photographic record.
44 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
CHAPTER VII.
VOLCANOES AND VOLCANIC FORCES.
1. I)efinition.-Volcahoes are openings in the
Earth's crust, out of which steam, various gases,
and molten rock or lava are forced.'
2. Structure. The matter ejected collects
about the volcanic opening, and builds up a cone-
shaped mountain. At the top of the mountain, is a
basin or depression, called the crater.
3. Volcanic craters vary in size, from a few
rods to more than a mile in diameter. They are
seldom more than four or five hundred feet in
depth, measuring from the rim of the crater to its
floor.2
4. The floor of the crater is the upper sur-
face of a solid plug of lava which extends below to
an unknown depth. This plug is generally blown
Crater of a Volcano. out in fragments whenever an eruption occurs.
5. At the surface of the crater floor, are sometimes one or more small cones-really
miniature volcanoes-which are nearly always emitting gases or small quantities of lava.
6. With each succeeding eruption, not only are the form and size of the crater
changed, but, owing to the lava, scorile, and ashes falling upon its sides, the whole mountain
is also greatly altered in outline and appearance.
7. The scoria of volcanoes consist of partly fused and blistered cinders, in appear-
.ance something like the clinkers that form in the grates of stoves burning soft coal.
Volcanic "ashes" are not ashes, but matter which has been finely divided or pulverized by
the eruption.
8. Cause of Eruption.-The origin of the forces which cause volcanic eruptions is not
known with certainty; it is usually attributed to the formation of steam from the water
"which finds a passage into the hot reservoirs.
9. The force required to raise a column of lava to the top of Cotopaxi exceeds 25,000
lbs. per square inch. But volcanic forces have hurled rocks and steam from the crater of
Vesuvius to a height of four miles. This force would hardly be greater were the volcanic
opening and reservoir beneath filled with gunpowder and exploded.
I The subterranean reservoirs in which the volcanic matter collects, and from which it is ejected, are not situated at
a great depth below the surface of the Earth. Such reservoirs, while they indicate internal heat, have no reference to the
"fluid interior of the Earth.
2 The diameter of the crater of Vesuvius has varied from 1,000 to 4,000 feet. That of Kilauea, the chief volcano of
"-the Sandwich islands, is at present about three miles long and one mile wide. Several craters of lunar volcanoes exceed-
50 miles in width.
VOLCANOES AND VOLCANIC FORCES. 45
10. With such enormous forces
acting within, the crust of the
Earth yields at the weakest
place. But the weakest places are e_ -i
in mountain ranges, where the _
crust has been already rent or
broken. Hence we find all of the A
volcanoes of the Earth scattered
along the main axes of mountain
systems.
11. Lines of Fissure.-Not -
infrequently,there occur chains of
volcanic mountains, all perhaps _
active, only a few miles distant
from one another. In such cases, it
seems probable that the volcanoes
are all situated on the same rent
or fissure.'
12. In at least one instance,
the volcanoes composing a chain
are connected by subterranean
channels. Thus while Vesuvius
has been active, Epomeo (6-ph'-
md-6), in the island of Ischia
(is'-k-a), a few miles distant, re-
mains quiet.
13. But when the eruptions Cotopaxi, the highest Volcano of South America. Eruption of 1855.
of Vesuvius cease, Epomeo at
once bursts forth with terrible energy. During the past 2,000 years, volcanic activity has
passed back and forth across the Phlegrean (fle'-gre-an) Fields, between Vesuvius and Ischia.
14. The Phlegrean Fields, situated on the north side of the bay of Naples, contain
about twenty-five well defined craters. Two of these, Lake Avernus and the Lucrine lake-
probably owing to subsidence-are filled with water.
15. Types of Eruption.-A few volcanoes are constantly active. Some, though dis.
'charging but little lava, are always emitting great quantities of stem and other vapors.
Others again, remain quiet for centuries, and then burst forth with frightful energy.
16. Stromboli (strom'-bo-lM), on one of the Lipari (lip'-ar-e) islands, is an example of
the former. It is constantly ejecting steam and lava, but with so little violence that one
may safely approach within a few rods of the crater. Of the latter class, Etna and Vesu-
vinre notable examples.
"17. Phenomena of Eruption.-When an eruption of a volcano of the latter type
occurs, the floor of the crater is first blown into the air in fragments. At the same time,
immense quantities of steam and gas are ejected, which, falling as a corrosive rain, cause
greater destruction even, than the flood of lava which follows.
On the island of Sumatra, less than 1,000 miles long, there are more than 100 active volcanic craters. In the Aleutian
islands, there are 31 active volcanoes on a line less than 500 miles in length. in Iceland, there are 13; in the Azores, 6; and
on the peninsula of Kamtschatka, 12 volcanic mountains, all showing signs of activity.
46 MONTEIITH'S NEW PHYSICAL GEOGRAPHY.
18. The flow of lava begins.
after the discharge of steam, being
at first violent, but afterwards steady
and quiet. When the reservoir of
.. -. lava has been exhausted, the erup-
tion gradually dies away with the es-
cape of gas.'
Successive Eruptions along the Line of Fissure. 19. Succeeding eruptions may
form new craters along the "line of
fissure." Indeed, it is seldom that this does not occur during violent eruptions. The accom-
panying figure shows the manner in which these new craters are formed.
20. During the eruption of Vesuvius, A.D. 79, a new crater opening on the side soon
built up a mountain exceeding Vesuvius in height. One rampart of the old crater has been
named Monte Summa; the new cone is called Vesuvius.
21. In volcanoes constantly active like Stromboli, the eruptions, occurring at
intervals of from ten to twenty minutes, consist merely of a puff of steam and other gases
forcing their way upward through the lava.
22. The seething lava may be seen in the crater, rising toward the top. At last, a
gigantic bubble forms, and bursting, hurls a shower of molten lava into the air.
23. The study of those volcanoes in and about the Mediterranean sea has contributed
the most reliable knowledge concerning the phenomena of volcanic outbursts.
24. Laws of Eruption.-Situated in the most populous and enlightened centers, they
have been studied for more than 2,000 years, and from their records the following conclu-
sions are drawn :-
An eruption following a long period of inactivity is apt to be violent, or else long con-
tinued.
Feeble and short eruptions occur at much shorter intervals of time.
Volcanoes constantly active show very feeble energy.
Eruptions are caused by the accumulations of steam and gases under great pressure.
25. Distribution of Volca-
noes. -The number of volcanic
mountains on the Earth having well
defined craters, exceeds 1,000; of
these, about 350 show signs of ac-\
tivity. Of the active volcanoes, about -__ _
117 are situated on continents; the
remainder are on islands.
26. Of the whole nuinber.
of volcanoes, fully nineteen-twen-
tieths are on the islands and coasts New craters formed along the flank of Etna during eruption of 1865.
of the Pacific ocean. By referring
to the chart of volcanoes, a chain of volcanic mountains may be traced from the southern
extremity of South America northward through the Andean and Rocky mountain systems.
Volcanic gases, with the exception of steam, are generally combinations of sulphur and of chlorine.
1 0 1. C I 0.7-J' 1O L 1X It /J/;', N7
i P,, 1. I ,. I I.. 1.A ...
| I I '' ..- .' .-. .i' ./ -
S: ,. ,. T :
I I--I
I r I (A I rf- N1 I c f
l Thi chain ext- i- t-- A,-;, th.n.l i.. l :- :I-," iula 4- Ali .ka an'l i.. Alutian.
i s a n.'..i c _utiu -.- thr. th chain of e.co.ntin'--tal islan c-s -.,at 4 A, .a.
'. A f-. w '. :- I. th.. *Il- .tItlIr of A -tr lia.it i, ji I on th r r 't v -.'lanic
fiss.U .Which 1 I -1 thl i_ i al I .il .l -l. .-. o I" t': g -r l -i C.' te* 'i v 1-
ean iv 6-irr.
N,**. tli, i-... l ,t Ii- ,. -at l in v le .-.": an' vi-:t c -l m..uvtai: ivieu' the:
diviin ..f ':ai. S ever i I l o wit ich j ole 1 .
; .- tT- 'o. .t v lu:i. vol i .ic .hi. i th"' A l'm- iti-e (ean. -iie
O -f t -,-, ext[l, I ro,. tl- lii r- t .- -. L -,, Antill,- -. .r .. .4cto a_ ot :. .
w l 1 in l" .. ;.I t
31. A ii...t .. b ..in. w ith t .. I .i.. i.r1 1 inl t nd k- 'thr. UI h
IJan .aven ; -, --i i-Iand. LI 1,l111. th. Az r. -. t. i- (aIlla -. n1.1 th,' C.p.. V-rI i"V"n'l .
From this chain a brai xtii-li. .It tihl Faror' .-It i i ',l- t.. ir' rth of ,Ia e I. i'. e
ca-ii-.. -i'' -. -
*i.volcantw n an: ..u; Il i nl 11.- 0.-t.ti l n. i-
G rab a' iIan a ll. 1, r l .. l' ..I t Il ll" '.' dLL: iilt' Il lr" thi chain. Thi v f- ra1
:3:1. Utillit. are tht, i ll l .-. .1 Ilf- t v l v .i .. the Earin th. Thi tlnruth .I i. ,hi w.-.ian
realize in its n ij.n th-e lintr- ,il tn1 l tlh.- r'atni s I- f thi ft l -rAtl con-tatlv at wi: l within the
Earth' crust.
t 4. a t-h r it lr tI. bi .-'-. itl l. -til,,1t aIn t .iD 1, hi i i. n i t1 ,..i t- '- til .Tiirn t of.
From this chain .-t. t.. il, t north ,t I :.h-, I.O. Tl- e
volh auoei s ar,.--ituiit'.... in LI: 4iil].ilf i il!l ,' ... Ili.IIltrl ill 1 ',+11" ,.
G rah DI{.nn' i-l nl. a n,.! .1- l.r-..' iiui l..1 ,' ,-,f ,tl,.r-,. nr>-- .i.+tna -, ,l,,n -'_ thii~ celinin. T hi t'..rm .
I:.;. !. tilit3.--'" V ,,l,.ani" .... re tIr,-- .-af,.-tv ,v 1\, ..- ... f tlh Earth." T i l, tr th ,,i thii w ,- .'-a,n
realize in ut,:lyinu' tlii lnltl.ill'i" ani th,- *.gr,-atn,- ."f tln: ,.',- -.,-cm -t nth- ,t w,,rk within the
Eart.h';. c(ri-t.
48 MONVTEITfH'S NEW PHYSICAL GEOGRAPHY.
35. Earthquakes frequently precede volcanic outbursts, and are often their only
warning. Indeed, it is not improbable that the same forces which cause the latter are also
the cause of the former.
36. Occurrence.-The most notable as well as the most destructive volcanic eruptions
of which there is any record, have occurred among the Mediterranean and the Javanese
groups. Of the first group, Vesuvius has been always the chief actor.1
37. In 1538, an eruption occurred in the Phlegrean Fields, soon building a mountain to
the height of 500 feet. This cone was named Monte Nuovo.
38. In the same year,Graham's island, a volcano off the coast of Sicily, was lifted above
the sea. During its short existence, its eruption was very violent, lava being thrown to a
height of 200 feet. When the eruption ceased, the island began to sink, and within two
years had wholly disappeared.
39. The most terrible eruptions have occurred in the Javanese group. The Javanese
records mention an outburst in the 12th century, during which Java and Sumatra, then a
single island, were separated and the strait of Sunda formed between them. The small
volcanic island Krakatu, remained above the ocean level, however, and has shown more or
less activity ever since.2
SPrior to A.D. 79, no eruptions of Vesuvius had been recorded. The cities of Stabiae, Herculaneum, and Pompeii
'(pom-payne) had been built at its base, and gardens and vineyards covered its sides nearly to the ramparts of the crater. In
A.D. 63, a violent earthquake occurred which overthrew many buildings, causing considerable loss of life and destruction of
property. The alarm consequent upon this disaster soon subsided, and for sixteen years there was nothing to arouse the
fears of the people dwelling within the doomed cities.
On the 24th of August, A.D. 79, a column of dense smoke (volcanic ashes) was observed rising from the top of the
mountain. The elder Pliny, then in command of the Roman fleet, desirous of learning the cause of the extraordinary occur-
rence, landed at Stabiae and hastened at once to the villa of his friend Pomponius. As night came on, streaks of fire appeared
on the sides of the mountain, and simultaneously with the darkening, showers of ashes, stones, and rain began to fall
thick and fast.
Perceiving that the villa would be soon destroyed, Pliny and his friend, with their servants, endeavored to make their
way to the harbor. Tying pillows on their heads to shield them from the increasing shower of stones, they attempted to
reach the sea shore, hoping to regain the nearest vessel of the fleet. Before they had reached a place of safety, however,
Pliny, overcome by stifling vapors, fell to the ground dead.
Morning dawned in the blackness of midnight. The air was still thick with falling ashes and loaded with sulphurous
vapors. When, at last, light was restored, a scene of inconceivable desolation appeared. The cities of Stabiae, Herculaneum,
and Pompeii, as well as the beautiful villas and gardens dotting the mountain side, had disappeared-all buried with their
inhabitants beneath the fallen ashes. For more than 1,600 years not a vestige of the ill-fated cities was found. In 1758,
some workmen digging a well came upon a building which proved to be a theatre of Herculaneum. Since that time a large
part of the city of Pompeii has been uncovered. From appearances, it seems probable the fatal shower occurred so suddenly
that many of the inhabitants perished in their houses.
After this eruption, Vesuvius remained quiet for over 100 years. Since that time, about twenty eruptions have taken
place, the last occurring in 1872. Professor Palmieri, who remained in his observatory on the side of the mountain during
this eruption, describes the spectacle as seeming as though the mountain were sweating fire at every pore." In all former
eruptions of Vesuvius, little else besides ashes was ejected. Later ones have been marked by the ejection of immense quan-
tities of lava.
"2 In August, 1883, without any warning there was an outburst, and Krakatu vomited an ink-black cloud which soon
involved the land in complete darkness. Then it began to rain scoriae and dust, and in a very few minutes,the greater part
-of northern Bantam, a fertile and populous country, was destroyed. Tremendous explosions hurled volcanic matter to a
distance of many miles; the sides of the volcano were blown into the sea, its structure collapsed, and the entire island slowly
:subsided. On the following morning,only half of the island was above the water's level." More than 100,000 people perished
by this convulsion.
Iceland contains thirteen volcanoes, of which Hecla and Skaptar Jdkul are the most noted. During an eruption of the
latter in 1873, the lava ejected formed a stream 50 miles long, having an average breadth of 15 miles.
VOLCANOES AND VOLCANIC FORCES. 49
40. There have been several eruptions of Etna.
'The most destructive occurred in 1669, during which -
,Catania was destroyed by the lava flood. Cotopaxi
in South America, and Kilauea in the Sandwich -
islands are celebrated for their violent outbursts.1
41. M.ud Volcanoes. Mud volcanoes and
.geysers are both forms of volcanic energy, each --
being caused by subterranean heat. Except in the 4
magnitude of their eruptions, they do not differ
greatly from volcanoes.
42. Geysers.-Geysers are hot springs occur-
ring in volcanic regions. At regular intervals, there
is a gentle overflow of water at the surface; then a
column of water is shot high into the air; and lastly, I
steam under great pressure escapes with a roar that u
may be heard for miles.
43. The geyser differs from other hot springs
only in having an irregular, long tube reaching
deep into the heated rocks.
44. Structure.- The geyser itself builds this
tube from the silica, of which sand is a familiar ex-
ample, which its waters dissolve while they are hot,
and again deposit around the spring on cooling.2
45. Phenomena of Eruption.-The water in -
the bottom of this tube may be heated many degrees
higher than the boiling point of water, but because Geyser in Yellowstone Park.
the pressure above is so great, the water cannot boil and hence steam cannot form.
46. By and by, the water in the center, or perhaps near the top of the tube, becomes
so hot that great bubbles of steam form and force some of the water out at the top of the
spring.
47. As soon as this takes place, the pressure at the lower part of the tube is removed,
and the water,heated so far above boiling point,at once flashes into steam. This it does-
not gradually, but instantly-and the force of the escaping steam throws a column of hot
"water often 200 feet or more into the air.
48. There are three regions where geysers chiefly occur. Iceland, New Zealand,
and the Yellowstone Park northwest of Wyoming. The latter, by far the most extensive,
contains about 10,000 mud volcanoes, geysers, and hot springs.
49. The geysers of the Firehole river in this park are the most wonderful in the
"world. The geyser basin is covered with snowy crystals of alkali and silica, often forming
the most exquisite and fantastic designs."3
SDuring 1888, Bogosloff, one of the Aleutian islands near Unalashka, and St. Augustin in Cook's Inlet-both volcanic
islands near Alaska-were rent by terrible eruptions. The former was leveled nearly to the water's edge; the latter was
split in twain
2h Hot alkaline waters only will dissolve sand. Bunsen found the waters of all the Iceland geysers to be alkaline, and
that none but alkaline springs were eruptive.
"3I In some places, the silica is deposited in a gelatinous condition to a depth of three or four inches. Trunks and
branches of trees immersed in these waters are quickly petrified."-Le Conte.
k./
50 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
50. There are seventy-one geysers in this region, from six of which the water is thrown
to a height exceeding 150 feet.
51. The Iceland region contains about 100 geysers, of which the Great Geyser is the
best known. Its eruptions occur regularly at intervals of an hour and a half, throwing a
column of water eighteen feet in diameter to a height of one hundred feet.'
52. The crater or basin of the Great Geyser is more than fifty feet in diameter, and the
surrounding wall is thirty feet in height. The tube is eighteen feet in diameter and extends
to a depth of eighty feet.
WHAT HAS BEEN TAUGHT IN CHAPTER VII.
Volcanoes are channels opening from the in- The most violent eruptions occur after long,
terior to the surface of the Earth. periods of inactivity.
Out of this opening, molten rock or lava, hotI About 350 volcanoes are known to be active,
gases, steam, and water are forced. 117 of which are on continental lands. The
The substances ejected from the volcano build remaining 233 are on islands.
up a cone-shaped mountain about the opening, The most remarkable chain of volcanoes skirts
forming at the top a cup-like depression,called the shores of the Pacific ocean, inclosing the divi-
the crater. sion of Oceanica, every island of which is a vol-
With every eruption, not only is the size, post- cano.
tion, and shape of the crater greatly changed, but A chain of submerged volcanoes extends
often the whole mountain is changed in appear- through the Atlantic ocean from Jan Ma yen
ance. island, one branch of which extends eastward
The origin of volcanic forces is generally as- through the Mediterranean sea.
cribed to the pressure of steam and other gases Mud volcanoes and geysers are forms of rol-
within the Earth. canic action, differing from volcanoes only in
The enormous pressure developed causes the magnitude and violence.
crust of the Earth to give way at the weakest The material ejected from geysers is always
point, which is along the axis of a mountain hot water, and the eruptions take place at reg-
system. ilar intervals.
Volcanoes situated on the same range are fre- The water of geysers being alkaline, dissolves
quently connected by subterranean channels, and i silica or sand. In cooling, the water again de-
the eruption often travels along the fissure formed posits the silica which it had dissolved.
by the broken crust. The silica thus deposited finally builds an ir-
Volcanoes are always situated near the sea regular tube, extending from the source of heat
coast. beneath to the surface of the Earth.
The average volcanic eruption consists of: 1st, The eruption of the geyser is due to the sad-
the blowing out of the crater floor and the dis- den formation of steam from water that has
charge of steam, water, etc.; 2nd, the discharge been heated above the boiling point.
of lava; 3rd, the escape of gases. The principal geyser regions of the world are
When volcanoes are constantly active, the the Yellowstone Park in the United States, and
eruptions are not violent. Iceland.
There is a small geyser region in the Malheur valley, in eastern Oregon. They are true spouting geysers, but are
insignificant in size and few in number. The geysers of Sonoma county, California. are not true geysers, but boiling mineral
springs. They are not eruptive.
EAR THQ UAKES. 51
CHAPTER V I II.
EAR THQUAKES.
1. Physical Phenomena.-Earthquakes are tremblings or vibrations of some part
of the Earth's crust. They are often connected with volcanic action, and it seems highly
probable that both are caused by the same forces.
2. Volcanic outbursts are nearly always preceded by earthquakes, which cease
after the eruption has occurred. The stoppage of volcanic action is frequently followed
by disastrous earth-shocks.
3. When the smoke from Cotopaxi ceases to appear, the people of Quito (ked-to) are
always in great dread of earthquakes. During the intervals when Vesuvius and Epomeo
are both quiet, the surrounding country is subject to violent shocks.
4. Earthquakes sometimes occur in regions remote from all volcanic centers.
These are undoubtedly brought about by the rising, the sinking, or by other movements
of large masses of the Earth's crust.'
5. Causes.-The cause of earthquakes of the first type is attributed to the explosive
formation of large volumes of steam or other gases in the hot interior of the Earth.
Except in the magnitude of their effect, such earthquakes are not unlike the jar following
the explosion of a great quantity of gunpowder.
i 6. Earthquakes of the second class are attributed to the gradual contraction of the
Earth's interior, in cooling. The shrinkage of the heated interior is much greater than that
of the overlying crust.
7. If the crust yields, the shrink- d
agek will be gradual and unnoticed;
but if it resists, by and by the increas- i'- |
ig force becomes great enough to I
break or crush the resisting parts. ', ,
8. Such a breaking or crushing- -
ot large masses of earth is sufficient
to produce the jarring or trembling -- -
that constitutes an earthquake. I- --_
S 9. Analysis of Shock.-If a _
stone be flung into the water, waves Faults' caused by the Sinking of Broken Strata.
are produced precisely like those of
the ground during an earthquake. At the spot where the stone strikes, the motion of the
Water is up-and-down. This movement makes a great number of circular waves, one
outside of the other, which spread over a large surface.
SThe coast of Chili was elevated from two to ten feet during an earthquake in 1835. An area of land exceeding
2,000 square miles in extent, lying near the mouth of the Indus, was wholly submerged by an earthquake occurring in the
North Indian ocean. During a severe earthquake, which in 1811 occurred in the Mississippi valley, several large bodies of
land near the mouth of the Ohio river, sunk, and to this day remain covered with water.
52 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
10. Above the center of the concentric circles, the motion consists of up-and-down
vibrations, but at all other places on the surface, it gradually acquires a rocking" motion.
In the following diagram, it is shown how the vibrations of the earth-wave may differ in
quality in different places.
A B C O E F G
0
Diagram to Illustrate the Motion and Direction of Earthquake-waves.
11. For instance, the shock may have originated at 0, the focus of the earthquake,
some distance below the surface. When the waves reach the surface at A, directly above
0, the vibrations are vertical, and are known as explosive or vertical waves. Waves of
this character are very destructive.
12. At some distance from A. as E, F, and G, the waves will no longer be up-and-
down; they will travel along the surface as rrl,';,,l waves. These are called "horizontal
waves of progression," or spreading surface waves. At a short distance from a point over
the focus of the earthshock-waves, as at B or C, the waves partake of both the rolling and
the vertical motion. Here the destructive effects are by far the greatest,.
"\
13. In a few instances, the ground has been twisted or whirled around, and buildings
have been turned so as to face in an opposite direction. Earthquakes of this kind are
very rare; they are usually known as vorticose, or whirling shocks, and are even more
destructive than vertical waves.
14. Velocity of Wave.- The velocity of earth-waves varies. being much greater in
hard than in loosely cohering rock. Careful experiments indicate an average of about
nineteen miles a minute.
15. Attending Phenomena.-Subterranean sounds occasionally precede earthquakes.
Sometimes,these sounds are like the roll of heavy wagons on the pavement; sometimes,like
the sharp reports of cannonading : and now and then, it resembles the crunching together
of rough surfaces of rock under immense pressure.
16. Occurrence.-According to Alexis Perrey, an average of nearly 600 earthquakes
happen yearly. This number includes all earth-tremblings- even those imperceptible
without the aid of instruments. It is plain, therefore, that in some part or other the
Earth's crust is constantly quaking.
EAR THQ UAKES. 53
17. Because earth- _
quakes are most fre- -__
quent in winter and
at full moon, it is
thought that the at-
tractive forces of the-
sun and the moon in-
crease the strain on the
Earth's crust, produc-
ing greater frequency -
of shocks. -
18. Distribu-
tion. Although
earthquakes occur in
all parts of the world,
they are most frequent
in volcanic countries,
and along the more
recently formed
mountain ranges. -
19. The regions in ___
which earthquakes are _a k .
most prevalent corre--- __-
spond closely to those tw
of volcanic formation. -
The principal earth- s -- ---l-e --- so s -o
quake region of North o -
America is on the Pa- -- --- --- -
cific coast, California The Earthquake at Arica and the Tidal Wave following.
especially being sub-
ject to frequent shocks. The Atlantic slope and the Mississippi valley, however, are occa-
sionally shaken.
20. Areas of Elevation and Subsidence.-There are also changes of level in the
Earth's crust which take place so gradually as to be imperceptible, except in long intervals
of time. For instance :-
The eastern coast of Greenland is slowly sinking.
The coast of North America, in the region of Labrador, is rising.
The northern part of Norway and Sweden is rising at the rate of six feet per
century.
The coast of Florida is slowly sinking.
The bed of the Pacific ocean in the region of Oceanica is sinking.
Memorable Earthquakes.-The earthquake at Riobamba, in 1797, was a striking example of both vertical
and whirling shocks. The city was directly over the earthquake focus, and the earth-wave was fully twelve feet in height.
Houses were thrown into the air, and the bodies of some of the victims were hurled to a height of a hundred feet across
the river. Although the shock lasted a few seconds only, nothing but heaps of stones were left of a once beautiful city.
More than 40,000 people perished.
The Lisbon earthquake of 1755 was frightfully destructive of life and property. At the moment of the first shock,
most of the buildings were overthrown. The cathedrals were crowded with people, who had gathered there to witness the
La
54 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
ceremonies of All Saints Day. Here the loss of life was appalling. Multitudes made their way to the sea shore, hoping
to flee from the crash of falling buildings;but an immense tidal wave, ninety feet in height, rolled in upon the shore and
.engulfed thousands whom the crash of the city had spared. Throngs had sought refuge on the new marble quay (ko), but
scarcely had they reached it, before the quay and
-- --- ,., -- :-- -- all who were on it sunk beneath the waters. The
loss of life in this catastrophe exceeded 60,000
Persons.
--In 1868, there were a great number of violent
"earthquakes within the Pacific volcanic belt.
r- South America, the Sandwich islands, and Cali-
Sfornia, were all more or less disturbed. On the
S coast of Peru, the cities of Tacua, Iquique (-kka),
it- Arequipa (ah-rf-kce'pah), and Arica (ah-re'kah), were
Destroyed. In Ecuador, the town of Cotocachi
(ko-to-ka che), sank out of view, and a lake of great
depth now covers its site.
t is The Calabrian earthquakes, during which so
et-"c many Italian towns and villages were destroyed,
S ._ seem to have been caused by the stoppage of
Stromboli, as they promptly ceased when that
S-_ c volcano resumed activity. At the time of these
-_ -earthquakes, several towns and villages entirely
disappeared, being engulfed within the earth.
Fort Sindree before it was submerged by the Earthquake of 1819. Near Terranova, a chasm opened into which a
part of the town fell to a distance of 300 feet.
Throughout the whole Compartamente' the earth was greatly shaken. Great land-slides occurred; deep chasms opened:
mud volcanoes and hot springs were formed; and in various places, bodies of land sank, the depressions being immediately
filled with water.
In 1819, an area of 2,000 square miles about the mouth of the Indus, in Hindoostan, was suddenly converted, by an
earthquake, into an inland sea. The fort and village of Sindree sank so much that only the tops of the fort, houses,
and trees remained above the water.
On the 28th of July, 1883, a destructive earthquake occurred on the island of Ischia, in the Bay of Naples. The
eastern part of the island, which is almost wholly
built up by the lava from Epomeo, was the center
of an earthshock which destroyed three towns.
At Casamicciola, where the earth-waves were ver-
tical, the shock was severest. The town was
totally destroyed and 7,000 people perished.
A mild shock ocnrered August 10, 1884,
which involved the New England and the Middle
States, reaching as far west as Cleveland, Ohio.
On Manhattan island,i the shock was vertical.
There are traditions among all peoples and i
in every language, of earthquakes that have been !
attended with the rising or the sinking of large
areas of land. The Indians of the old San Fran -
cisco Mission believe that San Francisco Bay was
once high above the water level, and sank during
an earthquake. There is one legend of this kind.
the story of Atlantis, that has more than ordi-
nary interest. According to Plato, Atlantis was
an island in the Atlantic ocean, opposite to the'
strait of Gibraltar. "It was the birth-place of Fort Sindree after the Earthquake.
civilization and the home of a mighty nation,
whose people colonized all of the adjoining country. But in time, there came a great convulsion of nature, and Atlantis
with its people sank into the ocean." It was the original seat of the Aryan or Indo-European family of nations, the
Semitic and the Turanian races. Ancient Egypt, it is asserted, was the oldest colony formed by the Atlanteans, and from
Atlantis, the Egyptians derived their civilization.
District. Part of New York City.
EAR THQ UAKES. 55
21. The Tidal Wave.
Tidal waves always follow earth-
quakes that originate near the
ocean. These waves, however,
must not be confused with the daily f t
tides, with which they have no con-
nection. N -
22. The tidal waves accompa-
Dnying the Lisbon earthquake were
"ninety feet high when they broke -.
upon the shore. Everything within
their reach was destroyed.
23. After the earthquake at
Arica, Peru, tidal waves sixty feet
in height rolled in for several hours,
destroying everything the earth- Fissures formed during the Calabrian Earthquakes.
shock had left. A United States
iron-clad vessel was carried from the harbor and stranded upon the beach two miles
from the shore. In several other instances, vessels at anchor have been tossed upon the
shore and left hopeless wrecks.
24. The'tidal wave is, without doubt, due to the up-and-down motion of the ground
just above the focus of the earthquake. The wave following the earthquake at Arica
traveled across the Pacific ocean. and in fourteen hours reached Japan, 10,000 miles distant.
WHAT HAS BEEN TAUGHT IN CHAPTER VIII.
Earthquakes are vibrations of some parts of In several instances, whirlidng shocks have
"the Earth's crust. been noticed.
In most hitstalnces, severe earthquakes are The velocity of the twue caries from 2,000
connected with volcanic action, usually preced- to 12,000 feet per second.
ing it, and ceasituqg wchen the eruption has itu- Earthtquakes oectcm with greatest frequency
shed. in volcantic regiolns, and alolof newtily-fornied
Earthquakes atwhich occurin i regions distant mnountalil ranges.
"from volcanic acticitU are due to the gradufal They are most freqIlentt duli rit winter months
shrinkage of the Earth's crust in cooling. (at tinie of full moo0n.
The earthslhock itself consists of series of There are other changes ofe' lel in the Earth's
waves originating at a center, a(td radiatilff ctrust, so iradial as to be noticed only in long
in every direction. iiterv"als of time.
The earth-waires ths formed posses diff'er- Farts of Greenland, of Florida, and nearly
eftt qualities at diffei-eent distances from the the whole of Oceantica (are sinking; while por-
center. tiojns of Labrador, Norwa.y, anll Sweden are
Over the center of disturbance the motion is rIisin.l.
,.ertical. As the distance from the center of Ocean wares of great height, called tidal
distirbate increases, the vertical graditally waves, f)-eqiuently follow earthquakes, which
chanie. to,, a horizontal watre. occur near, or in, the ocean.
56 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
O HA.PTER IX.
THE WATER OF TIHE ATMOSPHERE.
==---"-2 ---------
1. Ero_ e. cth V_
--
Watei. mii- -than any otir
agent in nature, has worn The Water of the Atmosphere.
and sculptured the surface
of the land, and given to it its present diversified appearance and picturesque beauty.
2. The hills have had their tops rounded off, and the plains and valleys have been
formed and smoothed over by water.
3. Those vast prairies of the Mississippi valley were made by the water of running
streams, which brought the material from the Rocky and the Appalachian mountains to fill
the ravines and level off the rugged surfaces.
4. All of those immense deposits of sedimentary rock, sometimes measuring miles in
thickness, have been worn away from older rock, pulverized, and distributed over the
Earth's surface by water.
5. Composition.-Water is composed of two gases, hydrogen and oxygen, combined
in the proportion of two volumes of the former to one of the latter. It freely absorbs air
and other gases, and likewise dissolves many of the minerals of the Earth with which it
comes in contact.1
I The oxygen weighs eight times as much as the hydrogen.
THE WATER OF THE ATMOSPHERE. 57
6. Forms of Water.- At ordinary temperatures,
pure water is a colorless, tasteless liquid. At 32 F., it p
becomes a solid, or freezes; and at 212' F., it changes to
steam.1
7. Expansion. The bulk or volume of water is
changed by heat. At 390 F. a pound of water occupies less
space than at any other temperature; but as the tempera-
ture lowers to the freezing point, the volume increases very
slightly-about one part in 400.
8. At the moment of freezing, the bulk increases about -- -
one-fourteenth. The expansive force of freezing water is
irresistible. Iron shells having walls an inch thick have Expansion of water at the moment of freezing.
been burst by freezing the water with which they were filled.
9. Above 390 F., the bulk of the water also increases with the temperature. Thus, if
100 gallons of water at 390 F. be heated to the boiling point, it will then measure nearly
110 gallons.
10. As water at the freezing point is lighter, bulk for bulk, than at 39" F., it is plain that
when the temperature approaches the freezing point, that part of the water below 39 F. will
rise, and the ice will form on the surface of the water instead of at the bottom.2
11. Specific Heat.-No other element on the Earth requires so much heat as water to
warm it. The heat is slowly absorbed, and as slowly given out again. It follows, therefore,
that all large bodies of water store up much of the sun's heat during summer and give it out
in winter, thereby tempering the climate of both seasons.
12. The heat required to warm a pound of water from 320 F. to 212 F. would warm
more than nine pounds of iron to the same temperature.
13. Latent Heat.-Whenever ice is melted a certain amount of heat is absorbed. For
instance, if a vessel filled with ice at 32 F. be placed upon the fire, the temperature of the
water will not rise above 32 F. until all the ice has been melted. A large amount of heat has
disappeared, having been used in melting the ice. If the water be changed back to ice all
of the heat again appears.3
14. Utility.-Without water, such forms of life as now dwell on the Earth could not
possibly exist. Our bodies are three-fourths water; the food we eat is four-fifths water; the
fruits of the tree and the vine are nine-tenths water. For many reasons, therefore, a wide
distribution of water is necessary to the growth and prosperity of a people.
SAt all temperatures, to a certain extent, water turns to vapor. Even ice and snow evaporate, if the air be dry. The
amount of water which air can thus hold in the form of vapor will be shown in another lesson.
"2" Ice forms only at the top, the mass of water remaining at 39' F. Had water become heavier as it cooled down to
the freezing point, a continual circulation would be kept up until the whole mass was cooled down to 32' F., when solidifi-
cation of the whole would ensue. Thus our lakes and rivers would be converted into solid masses of ice which the summer's
warmth would be insufficient to melt: and hence, the climate of our now temperate zone might approach in severity that
of the Arctic regions."--Roscoe.
3 When water boils, no matter how fierce the heat, the temperature remains at 212' F. until the whole of the water
has evaporated. This is because the heat has been used to change the water to steam. But when the steam is again con.
averted to water, all the heat is set free.
&
58 MONTEITH'S NEWI PHYSICAL GEOGRAPHY.
15. Atmospheric Water.-Every drop of water on the land, whether in wells or springs.
lakes or rivers, has been brought from the ocean by the winds, which, taking it up in the
form of vapor, pour it upon the land as rain. Let us learn the way in which this takes
place.
16. Air has the property of taking up water in the form of vapor. We may notice that
after a rain, the moisture soon disappears and the pools of water dry up. The air has
absorbed the moisture, which the heat of the sun has changed to an invisible vapor. This
Process is called evaporation.
17. Dew Point.-The amount of water the air can hold, depends on the temperature
of the latter. Warm air will contain a great deal more of moisture than cold air. When the:
air contains all the vapor it can hold, it is said to be saturated, or at the dew point.
TEMPERATURE, W'T OF VAPOR, TEMPERATURE, W'T OF VAPOR, TEMPERATURE, W'T OF VAPOR,
FAHRENHEIT. IN GRAIN. FAHRENHEIT. IN GRAINS. FAIIRENHEIT. IN GRAINS.
0' 0.55 65' 6.79 96, 17.65
10 0.84 700 8.00 980 18.69
20' 1.30 75' 9.37 100" 19.79
32' 2.13 80 10.95 101 20.36
40' 2.86 85' 12.75 102' 20.94
50' 4.09 90" 14.81 103' 21.53
55 4.86 92 15.71 104' 22.15
60' 5.75 94' 16.54 105 22.77
18. When, however, the temperature falls below the dew point, the excess of moisture?
appears either as rain, snow, hail, dew, fog, or clouds. In the foregoing table, you
will find the weight of water which a cubic foot of air, at different temperatures, may
contain.
19. Rain.-If air at 100 F. pass over the ocean, it will absorb a great amount of mois-
ture-nearly 20 grains per cubic foot. When this warm air strikes the cold mountain tops of
some continent, its temperature is suddenly lowered-perhaps to 65' F.
20. But at 65 F., the air can hold only one-third as much moisture as at the former tem-
perature. Hence the vapor is condensed or again changed to water, which, falling as rain,
saturates and fertilizes the porous soil of the Earth.
21. The average annual rainfall of the United States is about 39 inches; that of Europe
is 36 inches. The greatest annual rainfall occurs in the Himalaya mountains. Here, in
certain regions, the rainfall has exceeded 660 inches in one year.1
22. Snow.-Snow is formed when the vapor of water passes directly into a solid state.
It may therefore be called frozen moisture. Snow can occur only when the temperature
is at or below 32 F.
23. Examined with the microscope, snowflakes are seen to be crystals of wonderful
symmetry and beauty. Notice that each crystal is six-sided or six-pointed, and that the
angles are similar.
SThe distribution of rain will be considered in the chapter on climate.
THE WATER OF THE ATMOSPHERE. 59
24. Hail. -Hail is frozen rain.
and is usually formed at a great height.
Thunder and lightning often accompany
hail storms. Ordinarily, hail stones are
about the size of rain drops; but in many
instances they are much larger, some-
times exceeding two inches in diameter.
25. Hail storms are of very short
duration-seldom lasting longer than ten
or fifteen minutes, but they are always
severe while they last. The severest hail
storms of which there is any record, have
occurred in the northwestern part of the
Mississippi valley.'
26. Dew.-Dew is the moisture that
collects in little drops on the leaves and snow Crystals.
the grass, during clear, still nights.
27. To understand why and how dew thus forms, we must again consult the table on
page 58, to find how much moisture the air can contain at a given temperature.
28. If the temperature during the day is 80' F., the air may hold nearly 11 grains of
moisture per'cubic foot. But just after sunset, the surface of the Earth begins to cool
rapidly-much more rapidly than the air.
29. When the temperature has fallen to perhaps 600, the air near the ground, also cooled
to the same temperature, can therefore no longer hold more than half as much moisture.
The surplus is deposited as dew.
30. In the morning, as soon as the sun has warmed the Earth, it, in turn, warms the
air, which can once more hold the moisture. Hence the dew soon disappears by the vaporiza-
tion of the moisture which formed it.
31. Very frequently,there are nights during which no dew falls. If the sky be over-
cast with clouds, no dew will form, because the clouds do not permit the Earth to part with
the heat it has stored up during the day.
32. A strong wind will prevent the formation of dew, because none of the air remains
in contact with the Earth long enough to be cooled below the dew point.
33. Most frequently there is none deposited, because the atmosphere contains no more
moisture than it can hold at the lowest temperature which occurs during the night-that is.
the temperature does not sink to the dew point.
34. Dew forms most copiously in the vicinity of the sea coast, and in places well
supplied with fresh water. There are some localities far inland, in which dew seldom or
never falls.
35. M11ore dew falls near the ground than at a short distance above it. This is because
the temperature rises steadily as the distance from the ground increases.
1 \Vhen a large hail stone is cut in two, it is found to be composed of alternate layers of snow and ice. The cause of
this phenomenon is not known. It has been attributed to the whirling action of the wind, whereby the hail is carried suc-
cessively into warmer and colder layers of air, receiving a coating of water in the former, which freezes, and of snow in
the latter. This explanation is theoretical, and not at all satisfactory.
60 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
36. Frost.-Frost is frozen dew.
-- -- Whenever the temperature falls be-
S- -;- ilow 32 F., the moisture deposited
;. consists of minute icicles instead of
_- small drops of water.'
S--37. Fogs.-Fogs are masses of
vapor partly condensed, resting on
the surface of the Earth. It is thought
by some authorities that the minute
fs globules composing the fog are hol-
Slow-that is, air bubbles of exceed-
ingly small size; by others, it is
claimed that they are very small
drops of water.
38. Fogs prevail when the air
Sis just below the dew point and
cannot hold quite all of the moisture
p. present. With a rising temperature,
the fog disappears because the air
can then hold a greater amount of
moisture.
S39. Fogs seldom reach more than
-.. four or five hundred feet above the
-i' ground-often, not half that height.
i An observer on a mountain may fre-
i :_-- quently see the valley below envel-
S- -- oped in a dense fog, while above him
the sky is perfectly clear.
Various kinds of clouds. One bird in the illustration is in the Cirrus; two are in
the Cumulus; three, in the Stratus; and four, in the Nimbus. 40. Clouds.-Clouds differ from
fogs in position only, the latter rest-
ing on the ground, while the former are usually high in the air. Clouds are named according
to their form and appearance.
41. Cirrus' clouds are those light, feathery clouds which sailors call cat-tails. They
are always 'ery high, and it is probable that they consist of minute ice crystals.
42. Cumulus3 clouds are so called because they seem to be thrown up in heaps or
piles. The cumuli are summer clouds, and are supported by the warm, ascending currents of
air from the Earth. They begin to form after sunrise, are heaviest during the middle of the
day, and disappear after sunset.
43. Stratus4 clouds are the horizontal bands of cloud matter near the horizon, often
1 Frosts are far more apt to occur in valleys and river-bottom lands than on hill sides. The intelligent fruit-grower
recognizes this fact, and selects a hill or a mountain side for his orchard, rather than the alluvial bottom lands. Orchards
situated on a ridge of land, or on the foqt hills, are seldom troubled by early frosts, while those on the bottom lands frequently
fail year after year.
Cirrus.-From the Latin cirrus, a feather. 3 Cumulus.-Froin the Latin cutmulus, a heap or pile.
Stratus.-From the Latin stratus, a layer.
THE VATER OF THE ATMOSPHERE. Pl
seeming to be arranged in layers. They usually appear at sunset, and sometimes continue
through the night, but generally disappear at daybreak.
44. The nimbus1 is the storm cloud. It is of a dark hue, and shapeless. It hangs low
and covers the whole sky. The lower part of the nimbus cloud consists of raindrops; the
-central portion, of mist; and the upper, of fog, or cloud mist. Cumulus and stratus clouds
may become rain clouds, as they differ from the nimbus in form only.
45. Cirro-stratus, cumulo-stratus, and cirro-cumulus are modifications of those already
Described. Cirrus clouds, especially when they are observed at sea, are often the fore-
runners of a storm. No other clouds are watched with such interest by sailors as the cirrus
-cloud.
46. Economy.-Were it not for the moisture of the atmosphere, both the heat of day
".and the cold of night would be intolerable. But the small amount of vapor-scarcely one
Part in a hundred-acts as a screen which intercepts the fierce heat of the sun during the
-day, and gives it out at night.
47. In intercepting and absorbing the heat of the sun, the moisture of the air is more
t' han seventy times as powerful as the air itself.
48. In regions like the Libyan desert, where the air is unusually dry, the day tempera-
ture sometimes exceeds 140' F., while at night, water in shallow vessels may be frozen.
WHAT HAS BEEN TAUGHT IN CHAPTER IX.
The surface of the land owes its present ap- Air containing all the moisture it can hold at
pearance chiefly to the action of water, a given temperature, is said to be saturated.
Water is composed of two gaseous elements, Unless the air cools below the point of satura-
oxygen and hydrogen#, chemically combined. tion, no dew is deposited.
Below 32' F., water is a solid; and above 2120 Snow is formed when the vapor of waterpasses
.F., a vapor. at once into a solid state.
Water requires more heat to warm it than any Frost is frozen dew, forming only when the
-other substance occurring free ihn nature, and it temperature of the air sinks below the freezing
-also parts with its heat more slowly, point.
All fresh water in the Earth came from the Fogs are masses of vapor in a state of partial
-ocean. condensation, resting on or just above the Earth's
The air has the property of taking up water surface.
in the form of vapor. Clouds are classified as Cirrus, or feather
The warmer the air, the greater the amount clouds; Cumuluts, or pile clouds; Stratus, or
of moisture it will absorb. layer clouds ; and Nimbus, or rain clouds.
When air loaded irith, moisture is cooled, it The small amount of moisture in the atmos-
gives off the excess of moisture as rain, hail, here being a poor conductor of heat, shields the
8snowl, dew, fog, or clouds. Earth front much of the sun's heat during the
Dew is the moisture deposited on or near the (da/,, and prevents nmuchi of the heat received dnr-
ground when the air has slowly cooled below, the in i the day from escaping at night.
Point of saturation,.
SNimbus.-From the Latin nimbus, a storm cloud.
62 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
C HIAPTE E X.
TI-E WATERS OF THE CONTINENTS.
SPRINGS AND LAKES.
1. The water which is raised from the ocean as vapor, and is carried away by the
winds and poured upon the dry land as rain, evaporates, sinks into the ground, or else
flows off upon its surface. When it flows off upon the surface, rivers, creeks, and brooks
are formed; when it sinks into the ground, springs and underground reservoirs.
2. Origin of Springs.-A portion of the water which soaks into the ground sinks
until it comes to a layer of hard
rock or clay through which it can-
not pass, while another portion is
M.. X retained in the porous rock and
A. Isoil, just as it might be held by a.
sponge.1
S3. If a hole be sunk into water-
Ssoaked ground, it is immediately
.. filled with water forced out by the
Pressure of water above and around
-,"1 it. In this manner, our wells are
,, I kept full.
S. If there are cavities in the
ground, they also will be filled with
water. When such cavities are on
So s c sloping ground, the pressure of wa-
Section of the ground or rock, showing how wells are supplied.-A, The ter above forces it to the surface at
part through which the rain water percolates; C, Rock or clay impervious to
water; B, Seam or stratum in which the water passes; D, Level of water in a lower level.
porous ground.
5. The stream of water flowing
from this channel is a spring. Sometimes,there is a cavity or underground basin in which
the water collects, but quite as often,the whole supply is held in the porous soil, and trickles.
out through some channel which the water itself has made.
6. The water will flow so long as the level of the reservoir is higher than the spring.
When this is no longer the case, as after a long drought, the spring ceases to flow.
7. Occasionally, the water from running streams finds a small passage-way under
ground, and comes again to the surface at some distance from its starting point. Many
of the springs on the prairies and the plains may be thus explained.
8. The picture on the next page explains how springs are formed. The porous soil
into which the water soaks is underlaid by hard clay or by rock, through which it cannot.
readily pass.
Light,porous soils and sandstones will hold nearly half their bulk of water.
THE WATERS OF THE CONTINENTS. 63
9. Artesian Wells.-When an
underground reservoir is tapped by
drilling or boring through the over-
lying rock, the pressure is often so .i .
great as to force the water above the
surface. These artificial channels are
called artesian wells.'
10. Artesian wells have been A
sunk to great depths-2,300 feet or .
more-in order to reach underground .
streams of water. Sometimes the
Sweater spouts above the surface, but
oftener it does not quite reach to the
top of the ground.
11. Hot Springs.-In ordinary
cases, the temperature of spring water
Section of a Hill, whence issues a Spring.-A, Loose earmL or broken rock
varies from 50' to GO0 F.; but in many through which the water sinks; C, Solid rock or hard clay not penetrated by
places, there are springs whose waters water; B, Seam or channel in which the water flows.
are hot and even boiling.
12. Their heat is derived either
from the chemical decay of rocks,
or else from the heated volcanic mat-
-. -- u, water surrounding the reservoir. Most
of the known hot springs are in vol-
canic regions.
13. Mineral Springs.-The wa-
5t ters of many springs, in trickling
through porous rock, dissolve and
n t-- retain the more soluble minerals,
__ m such as salt, carbonate of soda,
.. lime, and various combinations of
D- A.2, sulphur. They are commonly called.
.._ "mineral" springs.'
14. Mineral spring waters usually
are hot, but some of the most cel-
ebrated in the world, as those of
Artesian Wells.-A, A, A, Strata impervious to water;-B, B, Seams or strata
of porous rock saturated with water;-D, D, Borings in the ground or rock, Saratoga, New York, and Seltzer,
called artesian wells. Germany, are cold springs.
SIn that part of southern California lying between the coast mountains and thePacific ocean, there are several thousand
artesian wells, ranging from 100 feet to 1,200 feet in depth. The first of these were spouting wells, but the number is now
so great, that but few of them force the water above the surface. By their means, millions of acres of land are now fruitful
which would be unproductive without them. A number of artesian wells have been successfully driven in the Great Desert,
by the orders of the French Government Survey.
2 Mineral springs may be calcareous, containing carbonate of lime; soda springs, containing soda; silicious springs, or-
geysers, containing silica or sand in solution ; sulphur springs, containing hydrogen sulphide or other sulphur compounds :
chalybeate springs, containing iron ; acid soda springs, containing large quantities of carbon dioxide. The latter are always
cod springs. "Seltzer," "Vichy," and "Congless" waters are taken from such springs,
,64 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
15. If carbonate of lime be present in the water of a spring, much of it is deposited.
If the water fall drop by drop, icicle-shaped deposits called stalactites are formed at the
ceiling, while similar deposits called stalagmites are built up from the floor of the cavity.'
16. Mineral Oil Springs.-In California, Pennsylvania, Syria, and Turkestan, tar
and petroleum springs abound. In the island of Trinidad, near the mouth of the Orinoco,
the accumulations of bitumen or mineral "pitch" have formed a large lake.
17. Periodical Springs.-Periodical or intermittent springs are those whose waters
flow at irregular intervals. It is thought that their irregular flow is due to the siphon-
shape of the channel through which the water is discharged.
18. Water Supply of Islands.-Supplies of fresh water are usually found even on
small islands-especially coral islands. Wells may be sunk from which fresh water is
*obtained, even though the surface of the water in the well be no higher than the level of
the surrounding ocean.
19. The explanation of this apparently strange fact is simple. After a heavy rain, the
water sinks into the sand, and being lighter than the sea-water, rests upon it, as is shown
in the accompanying cut.
-- --U- __ _
A, B, Sea level;-C, D, Fresh water from rain resting on salt water, with which it does not mix because it 1- liglher.
20. Formation of Lakes.-Much of the water that does not evaporate or sink into
the soil collects in natural depressions of land.
21. If it collect in this basin or depression more rapidly than it evaporates, a lake is
formed. The water either continues to collect until it rises to the rim of the basin and
overflows, or else it spreads over the land until it covers a surface so great that precisely
as much evaporates as flows into the basin.
22. Classification.-Thus we see there are two classes of lakes-those having out-
lets and those having none. The waters of the former are fresh; those of the latter are
usually salt. The latter are met with in great continental plains, where there is but little
chance for their waters to run off. For this reason, the lakes occurring in such regions are
commonly called "steppe" lakes.
23. Each continent has its lake-systems. The largest is in North America, which
alone contains a greater number of lakes than all the other continents together.
24. Lakes of North America.-The Great Lakes of North America have an area of
more than 100,000 square miles-scarcely less than the combined area of all the remaining
bodies of fresh water in the world. The basins drained by them, however, are but little
larger than the lakes themselves, as each basin is filled nearly to the brim.
SThe material thus deposited is usually known as travertine. Twigs, medallions, coins, etc., placed where they can be
sprayed with the waters of these springs, are quickly covered with a deposit of carbonate of lime. The so-called petrified
moss consists usually of the fine rootlets of plants covered with accretions of limestone.
2 This substance, variously called "pitch," "asphalt," and "brea," is much used in street-paving, for making a
tough, artificial building-stone, and also as a covering for foundation-walls.
THE WA TERS OF THE CONTINENTS. 65
_- -
-
Lake Superior. Lake Huron. Lake Erie. Niagara Lake Ontario. 1000 islands. Montreal. Quebec.
St. Mary's River. River and Falls.
A Sectional View of the Great Lakes and the St. Lawrence River, looking North.
25. The water of these lakes is supplied chiefly by rain, but partly by a few small
rivers. The average rainfall in the region of the lakes is 36 inches a year-an amount
sufficient to keep them full and to supply the St. Lawrence river, their outlet.
26. The situation of these lakes, in terraces, one higher than another, is an interesting
feature. The rivers draining the waters of these lakes contain falls and rapids.
27. Lakes Superior and Huron, the deepest of this group, have a depth of 1,008 and
S 702 feet, respectively. The bottom of the former is 409 feet below sea level.
28. Lake Erie has an average depth of about 120 feet. A severe storm stirs its waters
to the bottom. For this reason, and also because there is so little sea room, Lake Erie
during a storm is a very dangerous body of water for sailing-vessels.
29. A chain of smaller lakes lies northwest of the Great Lakes. Indeed, so closely
connected are the lakes, that water communication between Lake Superior and Hudson
Bay is sometimes possible for canoes.
30. An arc of a great circle drawn from a point a few miles west of Buffalo to the
western side of Geography island, near the mouth of the Mackenzie river, will pass through
nearly all of the more important fresh water lakes on the continent.
31. African Lakes.-The principal lake system of Africa is in the eastern part of the
continent, at an elevation varying from 3,000 to 5,000 feet above the sea level. Like the
Great Lakes, their basins are filled to the brim.
32. The lakes of Africa are in comparatively unexplored regions. Most of them
are drained by the Congo or Livingstone, and Nile rivers. The principal are Victoria, the
largest in the world, Albert, and Tanganyika (tahn-gahn-yee'kah).
33. Lake Tchad (chad), a fresh water lake in Soudan, has an area varying from
15,000 to 50,000 square miles, the latter being its area during the wet season. At high
water it overflows, the Bahr-el-Gazel being its outlet.
66 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
34. Lakes of South America.-There are but two lakes of considerable size in South
America, Maracaybo (mah-rah-kl'bo) and Titicaca (tit-e-kah'kah). The latter has an altitude
of 12,000 feet.
35. Lakes of Europe.-The lakes of Europe form two groups. Those in the Alpine
region are renowned for their beautiful scenery. The second group is situated in Russia,
Lake Lad'oga being the largest. Most of the latter group are steppe lakes.
36. The water of lake Elton, in Russia, contains about twenty-nine per cent. of
salt. In summer, many of the smaller steppe lakes of Russia dry up, leaving beds of
salt and other mineral matter.
S37. Lakes of Asia.-Lake Baikal (bi'kahl),in Siberia, is the largest fresh water lake in
Asia. Its waters are frozen six months in the year. Lake Sirikol, the source of the Oxus
river, has an altitude of 15,600 feet above the sea level.
38. Lakes of Australia.-Most of the Australian lakes are steppe lakes. They are
situated in the southern and southwestern part of the continent. Lakes Eyre, Gairdiner,
and Amadeus, are the most important.
39. Salt Lakes.-Of the various salt lakes, the Caspian, Dead, and Aral seas, and
Great Salt Lake, are the most noted. All but the last named are below the sea level.
40. The Caspian and Aral seas are thought to have been, in recent times, arms of
the ocean; but the fact that their waters are much fresher than those of the ocean,
makes this theory somewhat doubtful.
41. The Caspian sea receives the waters of the Ural, Volga, and several other large
rivers. The water supplied by these rivers is equal to the amount lost by evaporation.
42. The basin of the Caspian sea is a very large one and seems to be of recent forma-
tion. Petroleum, tar, and naphtha springs are numerous throughout the neighborhood of
the sea. Its surface is eighty-four feet below the ocean level.
43. During certain periods, large quantities of naphtha and petroleum accumulate on
the surface of the Caspian sea. In 1869, an extensive and destructive conflagration occurred
by the accidental ignition of these substances.
44. The Dead Sea, whose surface is 1312 feet below the ocean level, is the most
remarkable depression in the world. It is situated about eighteen miles east of Jeru-
salem, and extends over an area of 400 square miles.
45. The region in which it is situated is volcanic and is still subject to earthquakes.
There is strong evidence that this depression was formed about 1900 B. c., during an earth-
quake accompanied by volcanic action.'
46. The river Jordan is its only inlet of any importance, and it has no outlet. The
basin is a long one, but very narrow-hardly twenty-five miles in width.
47. The water level,during the rainy season, is about ten feet higher than in the dry
season of the year. This enormous surplus is evaporated during the hot summer months,
at which time the average temperature in the vicinity of the lake is about 93' F.
SThe site of the Dead Sea is the Vale of Siddim, which Lot chose for his habitation when he parted from
Abraham. Its climate was then vastly different from that of the present time. There were formerly two cities of
considerable importance-Sodom and Gomorrah. These were destroyed in the convulsion of nature, described in Gen.
xix, 28. The ruins of the ancient city, Zoar, have recently been discovered near the western shore.
THE WATERS OF THE CONTINENTS. 67
48. There is some evidence that the rainfall in Syria has been steadily decreasing
,during the last 2,000 years. Should this continue, the drying up of the Dead Sea is a
question of time only.
49. Sulphur, gypsum, pitch, and petroleum are found near the borders of the Dead
Sea. There is but one other body of water in the world (Lake Elton) which contains so
much of mineral salts in solution; every 100 lbs. of water contain 26 of salt.
50. Great Salt Lake.-Great Salt Lake of Utah is another remarkable example of
the steppe lakes. That the area of this lake was formerly much greater, may be seen by
the old shore lines, 900 feet higher than the present water-level. For the last twenty-five
years, however, there has been a steady increase in its depth.
51. There are several streams of water flowing into Great Salt Lake; the Jordan (of
Utah) is the largest. The soil,for many miles about this lake,is impregnated with lime, soda,
and potash, all of which are carried into the lake by tributary streams.
52. Origin of Salt Lakes.-We can now understand why the waters of those lakes
which have no outlets are salt. Soils and rock contain small quantities of salt and other
minerals which are dissolved by the water as it flows through them.
53. If the water flows into a lake having no outlet, it evaporates and leaves the
salt; but if there is an outlet, both water and salt are carried to the ocean.1
h --
WHAT HAS BEEN TAUGHT IN CHAPTER X.
Springs are formed by the water which, Lake-basins are natural depressions in the
falling as rain, sinks into the Earth. Earth's surface in which rain-water collects.
The water sinks until it meets a layer of If the water collect more rapidly than it
clay or of rock, through 'which it cannot pass. covpo'rates, a lake is formed.
It collects in 'underground reservoirs and Lakes are of two classes-those which have
channels, or saturates the porous soil. outlets and those which have none.
7When it emerges to the surface, the escaping The waters of the former are fresh; those of
water is called a spring. the latter, 'usually salt. The salt is dissolved
Underground streams of water are often from the soil through which the water flows.
tapped by boring through the overlying strata. The Great Lakes of North America constitute
The artificial springs thus formed are called the largest body of fresh water in the world.
artesian wells. The lake system of Africa ranks next in size
Spring waters have usually a temperature to that of North America.
varying from 40 to 600 F. The lakes of Asia and western Europe are
In volcanic regions, the temperature of their chiefly steppe or salt lakes.
waters, owing to their contact with heated T1he Dead, Caspian, and Aral seas are below
rocks, is often hot-sometimes even reaching the ocean-level.
S the boiling point. The Caspian sea is the largest salt lake in
Then the subterranean waters take up the the eastern hemisphere.
soluble substances of the rocks through which Great Salt Lake of Utah is the largest salt
they pass, mineral springs are formed. lake of the western hemisphere.
Well and spring waters also contain salt, although the amount is so small that it cannot be detected by the taste.
68 MONTEITH'S NE W PHYSICAL GEOGRAPHY.
C H APT ER XI.
"RI VERS AND D ILINAGE.
1. The water falling on the land in the form of
rain and snow is sufficient to cover the continents to
a depth of three and one-half feet each year.
2. Of this amount, perhaps two-thirds evaporates,
and the remaining third flows back to the source from
which it came-the ocean.'
3. The Beginning of a River.-The sources of
most rivers are in mountains, for here is the heaviest
N. fall of rain and snow; here, also, springs are most
abundant.
4. The water that trickles from a spring or is let
j loose from some snow drift high on the mountains,
forms a little rill which rushes down the steep slope
toward the plain below.
5. On its way,i.t is joined by other rills in their
journey to the ocean. The rivulet thus formed tum-
bles down the mountain slopes and over the pebbled
bottoms of the gullies which it has worn.
S. Other streams swell it to a mountain tor-
rent. Plunging over cliffs in cascades, or rushing
andown steep inclines in rapids, it cuts a channel into
Sthe hardest rock, and either tosses aside or else
ploughs through obstacles happening in its way.
A Mountain Streaml-The Upper Course.
SMtain Stream.-The Uer Cure 7. After a long and tumultuous passage,it reaches
the plain at the base of the mountains, where it receives the waters of other streams that
have had a similar journey.
s. Henceforth the conduct of the river is wholly changed. No longer able to carry the
load of silt and gravel which it has scoured from the bottom and sides of mountain gorges,
it drops all but the lighter portion and flows around obstacles which it cannot move.
9. So long as the current is swift it will carry this sediment, but check it ever so little,
and some of it sinks to the bottom to form a bar or "shallow."
10. The Middle Course.-When the stream has reached the lowlands, it is still heavily
laden with silt. At St. Louis, the river-if we take the Missouri and Mississippi as an
example-is still 1,300 miles'from.the Gulf, and 375 feet above the sea level. From St. Louis,
The foregoing statement must be considered as an average only. In certain regions, such as the Great Desert and Cen-
tral Asia, nearly or quite all of the water disappears by evaporation ; while in northern Asia and North America, the water
which evaporates is less than one-fifth of that which falls.
RIVERS ANVD DRAINAGE. 69
the river flows with slightly decreasing
velocity,on ground which it has itself spread Z.uhDER _.IT
over the valley. There are no banks that it
has not built for itself, and having built /
them, it can just as easily cut them away. ,.
-11. The Lower Course.-In time, the '
waters reach the Gulf of Mexico, after a con- -
tinuous passage of 4,100 miles. Here, the
current is checked by the ocean tides, and T-
the restless waters throw down the last rem-
nant of their burden of silt.
12. Thus we see that a river course may
consist of three parts: the upper course, F
where its work is erosive, or wearing; the
middle course, in which it is chiefly trans-
porting, or sediment-bearing; and the lower .. v
course, where it builds up land with the A River.-The middle course.
sediment brought from the upper course.
13. Effect of Velocity--A river whose current flows with a velocity of four miles
an hour will carry sixty-four times as much sediment as one flowing at the rate of two
miles an hour; consequently, a slight change in velocity makes a very great difference in
its carrying capacity.'
14. Filling the Channel.-Sediment is dropped in the lower course, because the cur-
rent is checked; and because the sediment is dropped, it is plain that the channel must
constantly fill up.
15. In time,the river has built its bed and its banks until they are higher than the sur-
rounding land. Until a season of high water, however, it still flows in its channel.
16. Then it overflows, cutting away the banks that it had itself placed there. Through
this break, or crevasse, the waters are poured over the surrounding lowlands.
17. The New Channel.-After the high
SA CREVASSE.ON THEI MISsiaslP PIv ER. waters have subsided, the river no longer
-. ---....- -_ ----- *i flows wholly in its old channel. In various
places, it has made a new one; and wherever
the channel has changed, the river at that
7 point has selected its bed in lower ground.
18. In this new channel the filling pro-
c' ess immediately begins, and continues till
another freshet turns its waters elsewhere.
: Thus has the work progressed for centuries.
A River.-Making a new channel. 19. Shifting of the Clhannel.-During
past ages, the waters of the Mississippi river
"It has been calculated that a velocity of three inches per second will tear up fine clay ; that six inches will lift fine
sand; eight inches, sand as coarse as linseed: and twelve inches, fine gravel; a velocity of twenty-four inches per second is
required to sweep angular stones of the size of a lien's egg."
70 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
must have flowed
in all parts of the
valley working
in the same man-
" ner that it works
now-building its
S banks higher than
Sthe surrounding
-- land, and then
breaking through
them.
20. So long as
ssit the Mississippi
..-flows, it will still
S- bear its burden of
Ss silt to the Gulf of
f ofMexico, and the
latter w ill de-
The Lower Course of a River.-Dropping its burden and forming a delta. crease i size un-
til it is dry land.
21. The territory north of the gulf was formerly an arm of the sea as far north as St.
Louis-or farther. All of that land has been formed from the silt brought down and depos-
ited by the waters of the river.
22. The lower course of most rivers-especially those flowing through level plains-
is usually very crooked and winding. The distance from St. Louis to the mouth of the
Mississippi in a straight line is 700 miles; by the river channel it is 1,300 miles.
23. Were the river to flow in a straight line, its fall would be 7 inches per mile; but,
flowing in its present course, the fall is less than 4 inches per mile.
24. Why it does not straighten its channel and thus increase its velocity seems strange,
until we consider that the current is so slow that the water cannot carry even the burden
it already holds. Hence, it drops the load and must ever afterward flow around it.
25. Building the Valley.-Thus we see that while in the upper course a river tends
to straighten its channel, in the lower course it constantly lengthens it.
26. The sediment carried from the uplands by rivers is enormous. In places,the deposits
are more than 1,000 feet deep. Much of the Great Central Plain has been built by the Mis-
sissippi and its tributaries.'
27. Bars.-If the mouth of a river face the tide wave, a bar is nearly always formed,
because the silt brought down by the river is forced back by the tide, and cannot be carried
far off shore by the river.
S' It must have been but yesterday that the mound-builders wrought in the valley, for in the few centuries that have
elapsed since then, the surface of the ground has risen only a few feet-not enough to bury their works out of sight. How
long ago, then, must it have been that the race lived there, whose pavements and cisterns of Roman brick now lie seventy
feet under ground ? And if we cannot answer this question, how slhall we figure up the sum of years it has taken to fill up
the valley a thousand feet deep with silt."-D. A. Curtis.
RIVERS AND DRAINAGE. 71
28. Bars thus formed are especially dangerous on the western
coasts of continents. Those at the mouth of the Columbia river
and the entrance of San Francisco bay are much feared by pilots.
29. If, however, the tide wave sweeps at right angles to the
current of the river at its mouth, much of the silt will be borne
away, while, if the tide be not strong, that which remains may
form a delta.
30. The Delta.-The figure on page 70 shows the manner in
which a river extends its channel into the sea. The network of
mouths and islands is called a "delta."' There the river drops
the last of its silt.
31. The stream must now force its way through the mud flats
which are constantly growing in size, and its waters must twice a
day be pushed back by the tide. For this reason, little or none of
the sediment can be carried beyond the delta.2
32. About 7,500,000,000 cubic feet of sediment are brought
down yearly by the Mississippi
river-enough to cover a square
mile of land to the depth of more
than 270 feet.
Chasm of Tugaloo River, Georgia.
33. Thus, for more than fifty
miles the Mississippi has pushed its way into the sea, bor-
dered on each side by narrow strips of land. These border
strips are natural levees made by the river itself.
34. The Po, in northern Italy, is remarkable for the
rapidity with which it has built its delta. Since the time of
SAugustus Caesar, this delta has been pushed seaward 20
miles. During the reign of that emperor, the town of Adria,
now 20 miles inland, was a seaport.3
35. Rapids and Cataracts.-It sometimes happens
That the water of a river descends abruptly from a higher to
a lower level. This is accomplished either by falls or by
rapids.
36. If, in the higher level, there is a surface-layer of
hard rock, a fall or cascade is the result. But if the upper
1 surface is soft and easily worn away, rapids are formed
Tocoa Falls, Georgia. instead.
i Delta.-The name of the Greek letter D, made thus, A.
2 The delta of the Mississippi river has an area of 14,000 square miles ; the deltas of the Nile and the Ganges cover an
extent of 20,000 square miles each.
3 In order to guard against overflows, the lower course of the Po has been flanked by levees until the present bed of
the river is much higher than the land on either side, owing to the constant deposition of sediment. Certainly a time must
come when the levees will break and the channel of the river change. The same policy of levee building has been adopted
in the case of the lower Sacramento river, where to the natural accumulation of sediment have been added the tailings"
from the hydraulic mines. With the lower Mississippi, a different plan has been followed. Here, the levees and jetties have
been constructed in such a manner as to increase the velocity of the current, thereby forcing the water to scour out the channel
instead of filling it. This carries silt out beyond the delta.
72 MONTEITH'S NE-W PHYSICAL GEOGRAPHY.
37. The cataract between lakes Erie
Sand Ontario, where the Niagara river
-- falls to a lower terrace, is one of the
S-most celebrated in the world. The Yo-
semite falls, in California, are an extra-
ordinary example of mountain cascades;
one of them having an uninterrupted
4 e fall of 1.500 feet. The total descent of
the water is about 2,600 feet.
38. The falls of the Zambeze, about
360 feet in height, rank next to those of
Rthe Niagara river. The Cascade moun-
o tains are celebrated for the number and
beauty of their waterfalls. The Cascades
Lachine Rapids, St. Lawrence River. of the Santiam, Willamette, and Co-
lumbia rivers, of Oregon, are unsurpassed
for their beauty and grandeur by any others in the world.
39. Erosive Action.-The wearing or erosive power of rivers is almost beyond belief.
The cafion of the Colorado has been cut almost vertically to a depth, in many places, of more
than a mile.
-10. Deep gorges, sometimes exceeding 3,000 feet, have likewise been cut by the Columbia
river and its tributaries. The cation of Crooked river is especially notable.
41. River Basins.-A river system comprises a river and all its branches. The surface
of land drained by a river system is its basin or territory.
42. The rimt of a river basin is called a watershed or divide. Generally,the divide is e
a mountain range, but sometimes it is an imperceptible ridge in some plain.
43. Divides.-The Height of Land which is the divide between the Great Lakes and
the Mississippi river is a plain. The
water taken from Chicago river to '
feed a canal discharging into a trib- .:L.
utary of the Illinois, is lifted by ma- I .
chinery but five feet. -
44. The most notable divide of .
North America is in the Rocky moun- "
tains. Separated by a few miles arc
the sources of the Missouri, the Co-'
lumbia, the Athabasca, and the Sas-
katahewan.
46.-Drainage. North America .
contains several large drainage basins, ; .
of which the Mississippi is the most. -
important and the largest. East of '
the Appalachian system the slope is -
drained by numerous, short rivers flow- -~--" I
ing into the Atlantic ocean. The Great Continental Divide.
RIVERS AND DRAINAGE. 73
46. The rim of the Mississippi basin is formed by the Rocky mountains, the Height
of Land, and the Appalachian mountains. This basin covers an area of one and a quarter
million square miles.
47. The Pacific slope is drained by the Yukon, Columbia, Sacramento, and San
Joaquin (wah-keen') systems. The Yukon river is second to the Mississippi only,in volume.
Its course, though, is in an unexplored region.
48. A few river basins, such as the Humboldt, the Mojave (mo-hah'-re). and the Amar--
gosa-all in the Great Basin-have no outlet to the sea.
49. Of South America, the great drainage basins are the Amazon, the Orinoco,
and the La Plata. During the rainy season, the channels of the Amazon and the Orinoco.
are not large enough to carry off the surplus waters. Hence their plains are often flooded.
West of the Andes, the slope is abrupt, and the rivers are short. There are no well-defined
basins.
50. In Africa, the principal river basins are those of the Nile, the Livingstone or
Congo, the Zambeze (zam-bO'-za), and the Niger (ni'-jer). The Nile carries off the surplus
waters of lakes Albert and Victoria, situated 3,800 feet above sea level. The yearly rise of
water floods a large area of the Nile valley, covering it with a layer of rich soil.
51. The drainage basins of Europe, though numerous, are much smaller than that
of the Mississippi. Those of the Volga and the Danube are the largest. The basins of the
Rhine and the Rhone are the most important. The principal divide of Europe occurs in the
plains, and is formed by the slopes of the Valdai Hills. The sources of nearly all the large
rivers of Europe, except the Danube, are on the slopes of this divide.
52. In Asia, the slopes of the Stanovoy and the Himalaya mountains form the chief
watersheds. These mountains enclose a depression of land dotted with steppe lakes, from
which the rainfall is almost wholly removed by evaporation.
53. The eastern and the southern surface slope to the Pacific and Indian oceans respec-
tively. These slopes are drained by large rivers, the principal of-which are the Amoor,
Hoang, Yang-tse, Irrawaddy, Brahmapootra, Cambodia, and Ganges.
54. The Amoor river and its basin are of great importance to Russia. The valley of the
Amoor is fertile, producing large crops of grain. The
river is the only great inland highway in eastern Russia.
It is navigable for 1,500 miles.
55. The Yang-tse Kiang I is also an important inland
highway of eastern Asia. It is navigable for large ships
250 miles from its mouth, and for river steamers,450 miles
farther.
56. The Ganges is navigable for a distance of 1,500
miles from its delta, and a greater number of vessels ply
on its waters than on any other river in the world. It dis-
charges its waters through a great net-work of channels,
on one of which, the Hoogly river, Calcutta is situated.
The land about the delta of the Ganges is low and swampy :
it is called the Sunderbunds.2
I Ho and Kiang mean river.
'The Ganges is the sacred river of India, and is one of the most celebrated in the world. For fertility and richness.
the valley of the Ganges has but few, if any, equals in the world.
74 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
57. Economy of Rivers.-Rivers are free and natural highways, and as such, their
importance cannot be over estimated. Without a navigable river, the settlement of a country
is usually slow and restricted.
58. In the growth and settlement of the United States, rivers have always constituted
the pioneer transportation lines, and have played a most important part in the prosperity of
the country. Therefore, the Government has wisely forbidden the obstruction of navigable
channels, and their control is placed wholly in the power of Congress.'
WHAT HAS BEEN TAUGHT IN CHAPTER XI.
One-third of the water falling upon the Earth branches; and a river-basin, the.erfirTer drained
finds its way back to the ocean. by the river system.
This water collects in channels, called, accord- The rim of the basin forms a watershed or
ing to their size, rills, rivulets, brooks, creeks, divide.
and rivers. The principal divide of North America is that
In the upper course of a river, the current is from whose slopes the Athabasca, the Saskatch-
rapid, always cutting and wearing its channel ewan, the Colambia, and the 3lissouri river
deeper. radiate.
In the middle course, it carries much of the South America possesses but few well-defined
lighter sediment taken from the upper portion. drainage basins, its main watershed being the
In the lower course, the river deposits the sed- Andes mountains.
intent, building its banks and bed, often extend- The chief drainage basins of Africa are those
ing them some distance into the sea. of the Nile, Livingstone, Niger, and Zambeze
The sediment-carrying power of a river de- rivers.
pends wholly upon the velocity of its current. The chief watersheds of Asia are the Ilima-
In the upper and the middle course, a river laya and the Stanovoy mountains, from whose
changes its channel but slightly, while in the outer slopes the rivers flow in every direction.
lower part, it flows around the obstacles it has The chief watersheds of Europe are the Valdai
deposited in its own way. Hills and the Alps; the largest basins, those whose
A rirer system consists of a river and its rivers flow into the Caspian and Black seas.
'To the Teacher.-In the study of hydrographic basins, the following exercise will be found an excellent one:-
On a good map of the United States draw a very light pencil line which shall separate the Mississippi and its tribu-
taries from these rivers flowing into any other water than the Gulf of Mexico. This line may enclose all rivers east of the
Rocky mountains, and all west of the Appalachian divide. In the same manner, the chief hydrographic basins of South
America may be defined. In separating the basin of the Orinoco from that of the Amazon, it must be remembered that the
Cassiquiare river divides or forks, sending part of its waters into the Orinoco, and part into the Rio Negro, a tributary of the
Amazon. On the map of Europe, from the Valdai Hills draw a line which shall separate the rivers flowing into the Arctic
ocean, the Baltic and North seas from those that flow into the Mediterranean, Caspian, and Black seas. This line, which
should terminate at the strait of Gibraltar, is the principal divide between high and low Europe. These lines, after being
inspected and corrected by the teacher, may be drawn with red ink.
The formation of terraces along river valleys suggests that there have been occasional periods of rest in the elevation
of continents. "I counted to-day forty-one distinct ledges or shelves of terrace embraced between our water-line and the
syenitic ridges through which Mary river forces itself. These shelves, though sometimes merged into each other, presented
distinct and recognizable embankments or escarps of elevation. This imposing series of ledges carried you in forty-one
gigantic steps to an elevation of 480 feet; and as the first rudiments of these ancient beaches left the granite which had
once formed the barrier sea-coast, you could trace the passing from Drift-strewn, rocky barricades to clearly-defined and
gracefully curved shelves of shingle and pebbles. The studies of these terraced beaches at various points on the northern
coast of Greenland are more imposing and on a larger scale than those usually regarded by geologists as indicative of sec-
ular uplift of coast."-Kane's Arctic Erplorations.
AVALANCHES, GLACIERS, AND ICEBERGS. 75
C H AP T ER X I I.
AVALANCIITES, GLACIERS, A- D ICEBERIGS.
1 e. ccnumulation of Snow.-More snow falls between the
-- ; l.it- ....t i;.000 and 9,000 feet than at any other elevations.
:!..4.: 110 feet, but little snow accumulates, and only a very
-' -inll .iii...int falls above an elevation of 11.000 feet.'
Si -. I the Alps,the yearly snow-fall is about sixty feet in
S.: .l'thl. In, the Cascade mountains of North America, the snow-
-- 1,ll -I.ui-!Ilerably exceeds this amount, the snow often accumu-
S' 1,1,111 t.. ; depth of sixty feet.
'.. rl*emoval of the Snow.-Except on the highest mountain-
S '-.ak tih. snow is removed by the summer's heat, but in high
Si t i.it:es. there are large areas of mountain territory perpetually
1 '.Ire with snow. In the latter case, it might seem as though
th.. mii.intains would be covered deeper and deeper, until they
t' in tll:l an immense snow-bank many times larger than the
S ,, iii'ita7iin itself; but there are several agents in nature that
combine to prevent this.
S4. The great weight of a snow-drift is often
sufficient to melt it at the bottom, thus preventing
i further accumulation.
S5. Evaporation is another agent. Without
melting, snow and ice evaporate just as certainly
... ^ -LsTIE R as water does, only not so rapidly. On the tops
S of mountains where the air does not press so
An Avalanche in the Rocky Mountains. heavily, evaporation goes on much more rapidly
than at the sea-level.
6. Wet clothes hanging out-of-doors soon dry, although they may be frozen stiff.
Muddy roads that have frozen over, often become dry and dusty without thawing.
7. The wind is another agent. On high mountain crags, the wind often blows with
a velocity of 100 miles an hour. Such a gale quickly clears the snow from all exposed
places, drifting and packing it solid in the ravines and canfons.
8. The larger part of the snow and ice is carried down the mountain side in the
form of avalanches or glaciers.
v. Avalanches.-On account of their position in the center of a thickly populated
district, more is known about the avalanches and glaciers of the Alps than those of any
Sthrregion in the world.
SIn the Frigid and Torrid zones, however, the case is different. In the Torrid zone, the limit of perpetual snow is
-about 16,000 feet above the sea-level. In the Frigid zone,the limit of perpetual snow descends to the level of the ocean.
"76 MQNTE'ITH'S NEW PHYSICAL GEOGRAPHY,
10. The Alpine peaks, having abrupt slopes, are favorable for the occurrence
of avalanches. When the mass of snow becomes so great that it can no longer
rest on the steep slopes of the mountain, there is a sharp crack ; a cleft in the snow-
field appears, and then an immense mass of snow dashes down the slope with terrific
violence.'
11. The instant the avalanche stops, the flakes of snow are changed by the great
pressure to granules of ice. These quickly cohere, and the whole mass of moving snow
becomes instantly as solid as ice.
12. Avalanches in the Alps occur with great frequency. Often, during a single day, a
dozen or more will dash with a low, sullen roar down the mountain-side, sometimes
burying villages and bearing fearful destruction in their course.' They are less prevalent
in the Rocky and Sierra Nevada mountains, because the slopes of the latter are less abrupt
than those of the Alps.
13. Glaciers.-The snow which has tumbled down the mountain-side in the form of
avalanches and much that has fallen in a natural manner is removed in a singular way.
14. Winds gradually drift the snow into ravines and mountain-valleys. From
these, it often extends into the region of cultivated fields and far below the altitude which
marks the limit of perpetual snow.
15. If we examine this mass of snow and ice, we shall find that it is moving slowly
down the ravine-sometimes not more than a few inches a month, but often twenty or
thirty inches a day.
16. This moving mass of snow and ice is a glacier. Its current, resembling that of
a river, is swiftest at the surface and slowest at the sides and bottom. The velocity of a
glacier depends on the temperature of the ice, the steepness of the slope, and also the depth
of the ice. Twelve or fifteen inches a day is an average rate.
17. The upper part of the glacier consists of snow sometimes more or less compact,
but often as soft and flaky as when it fell from the clouds.
18. Very soon after it begins its journey,the alternate thawing and freezing change the
snow-flakes to small rounded grains of ice, called neve (ndvd). In time, much of the neve,
In these mountains,the greatest accumulation of snow takes place at an elevation of eight or nine thousand feet, the
peaks which extend above this height being quite bare.
"2 Having crossed about three quarters the breadth of the couloir, the leading men sunk considerably above their
waists. I tried to follow Bennen, but sank up to my waist. So I went through the furrow, holding my arms
close to my body so as not to touch the sides. As the snow was good on the other side, we came to the false conclusion that
the snow was accidentally softer there than elsewhere. Boisonnet made a few steps in advance, when we heard a deep
cutting sound. The snow-field had split in two about fourteen or fifteen feet above us. The cleft was at first quite
narrow, not more than an inch broad. An awful silence ensued: it lasted but a few seconds, and then it was broken by
Bennen's voice, 'Wir sind alle verloren.' (We are all lost.) They were his last words. The ground on which we
stood began to move slowly. I soon sank to my shoulders and began descending backwards. The speed of the avalanche
increased rapidly, and before long I was covered up with snow. I was suffocating, when with a jerk I suddenly came to
the surface again. It was the most awful sight I ever witnessed. Around me, I heard the horrid hissing of the snow, and
far before me the thundering of the foremost part of the avalanche. At last, I noticed that I was moving more slowly;
then I saw the pieces of snow in front of me stop, and I heard, on a large scale, the same creaking sound that is produced
when a heavy cart passes over hard frozen snow. I felt that I had stopped, and threw up my hands to protect my head,
"* but was covered up with the snow coming behind me. I made vain efforts to extricate my arms, but found it
impossible. A sudden exclamation of surprise! Rebot had seen my hands. I was at length taken
out: the snow had to be cut with an axe down to my feet before I could be pulled out."-TYNDAIL.
A VALANCHES, GLACIERS, AND ICEBERGS. 77
by the constant pressure of its par- ---_ --
tides, loses the air it had contained '--
and becomes welded into solid ice.- ..
19. C1revasses. -Numerous fis-
sures, called crevasses, are formed -
in a glacier by irregularities in its
course, in the inclination of its bed. -
and in the velocity with which it
moves. -
20. Moraines.- Rocks which
have been broken from the cliffs.
together with stones, gravel, and
other materials which have rolled.
or fallen, upon the glacier are car- .
ried along with it. Such accumula-
tions are called moraines.
21. Those which are at the sides
of the glacier are called lateral mo- t t
raines. Viewed from the glacier,
they resemble long walls. When
two glaciers enter the same valley,
their moraines which meet and are
carried thence along, or near, the
center of the main glacier, form a
medial moraine.
22. The great mass of stones. I..
gravel, and other materials which
have been deposited at the end of a .,
glacier, is called a terminal moraine.
It sometimes covers an area of more
than a square mile and exceeds a
hundred feet in height.
23. A river issues from the lower
end of a glacier. The Rhine, Rhone,
Po, and a number of the tributaries
of the Danube have their sources ,t *
among the Alpine glaciers.2 An Alpine Glacier. The beginning of a river.
S The velocity with which a glacier moves is greater in the center than at the sides, and at the surface than at the
bottom. It is greater in summer than in winter, and in mid-day than at night. The greater the slope of the bed, the
greater is the velocity.
S The glaciers of the Alps have their sources far above the snow-line, while their terminal moraines are about 5,000
feet below it. The snow-line on the Alps is about 9,003 feet above the level of the sea. For the formation of glaciers, it is
necessary that the mountains extend above the snow-line, and that there be alternate freezing and thnwings.
78 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
24. The water issuing from the
lower end of a glacier is always
muddy, because it contains substances
that are worn from the bottom and
the banks of the ravine.
..5. Distribution.-There are many
large glaciers in the Himalaya moun-
tains, but they are comparatively un-
known. The glaciers of Mts. Rainier
and Shasta in the United States are
equal in size to the largest Alpine,
glaciers.
26. By far the largest glaciers in
Sthe world are those of Greenland and
Alaska. Humboldt glacier in Green-
Sland is said to be sixty miles in
breadth.
27. Icebergs.-Icebergs are masses
of ice broken from glaciers, where
the latter terminate on a sea-coast.
"The end of the glacier is pushed
into the water until a large mass is
broken off.
28. The mass of ice thus broken
off floats along with some ocean cur-
rent, until it is melted by the warmer
water into which it floats.
Floating Iceberg.
29. Icebergs from the Greenland
glaciers drift southward in the Arctic current, through Baffin Bay. Near Newfoundland,
they meet the warm water of the Gulf Stream and drift between the opposing currents
until they are melted.
30. It is thought by many geographers that the banks or shallows east of the galf
of St. Lawrence have been formed by the sand, gravel, and boulders, carried there
by means of icebergs which, on melting, drop their load to the bottom of the sea.
31. From an eighth to a tenth of the iceberg is above water, the remainder
being below the surface. On one or two occasions, icebergs projecting a thousand feet
above water, have been observed; but ordinarily, they seldom exceed one or two hundred
feet in height above the surface.
32. Ancient Glaciation.-The transporting power of glaciers is wonderful. A wide
stretch of country between the Baltic and the Black sea is covered with boulders and
drift, carried from the Scandinavian mountains by glaciers of a former geological
period.
33. Portions of England and Scotland are also covered with similar drift, called
"till." These boulders are distinguished by their faces, which are ground flat and scored
with parallel scratches.
AVALANCHES, GLACIERS, AND ICEBERGS. 79
34. In examining that part of Europe which comprises the Scandinavian peninsula,
Great Britain, and Ireland, one cannot help noticing the frayed and ragged appearance
of their western coasts.
35. These notches in the coast are the work of glaciers which, originating in the higher
portions of the Scandinavian mountains, furrowed and scraped the surface of northwestern
Europe into its present shape.
36. In North America, the work of glaciers has been of even greater magnitude.
Here, the ice-flood came from the north and extended as far south as the Ohio river.
37. The peculiar shape of most of the older North American lakes is, by many geologists,
attributed to glacial action.
38. Observe that those of the northern and northeastern part, especially, are long and
very narrow. Their lines of greatest length are usually parallel; but occasionally, a group of
lakes, like those of central New York, are ranged like the spokes of a wheel and point to
a common center.
39. Late researches have shown that lakes occur chiefly in regions covered with
"glacial boulders, and that they are comparatively rare in those parts of the Earth that are
free from glacial action.
WHAT HAS BEEN TAUGHT IN CHAPTER XII.
The greatest amount of snow falls between The lower end of a glacier usually forms
the altitudes of 6,000 and 9,000 feet; little the source of a river. Most of the rivers of
falls above the latter altitude. central Europe and many of those in Asia
This accumulation of snow is removed by originate in this manner.
,wind, avalanches, glaciers, evaporation, and by Glaciers occur in the Himalaya, the Rocky,
melting. and many other mountain-ranges, the largest
On account of the abrupt slopes of the mount- in the world being those of Greenland and
gains, avalanches are most frequent in the Alps, Alaska.
and they usually take place just after heavy Icebergs are masses of ice broken from gla-
snow-storms. ciers which terminate on the shores of polar
The snow brought down the mountain side regions.
by avalanches and drifted into the caitons by The icebergs, broken from glaciers of Green-
the wind, forms glaciers. land, drift southward with the Arctic current
The motion of a glacier resembles that of a until they meet the warm waters of the Gulf
river, being greatest at the center of its upper Stream.
surface and slowest at the bottom and the sides. Various parts of the world are strewn with
The source of a glacier is fine snow, called boulders, left by glaciers during past geolog-
neve, which is converted by pressure into ice. ical ages.
The glacier, in its central and lower parts, The configuration of northwestern Europe,
is seamed with crevasses, extending partly or as well as its notched and ragged coast lines,
wholly across it. are due to glacial action.
The rocks, gravel, and earth which are In North America, there are evidences of
piled up at the sides of the glacier, or per- glacial action as far south as the Ohio river.
haps pushed along before it, constitute its The lakes of the northern part of North
moraines. America are often attributed to glacial action.
~ "---- -' : -O'
Oi l
-~~~~~~ r"A~? lsa ;3~~~~- ... .:...- ---.,. . ..-
~~~3 ..--a- I,
I m
~~~~~~- 1 ,,,.. , '.-4
5tc
A Calm. THE OCEAN. A Storm,
OCEAN WATERS. 81
CHAPTER XI. T
OCEAN WATER R S.
1. Area and Extent.-Of the 144,000,000 square miles of the Earth's crust covered by
Sweater, three-fifths lie south of the equator, and the remainder north of it.
Included in this area,are two million square miles about the North Pole and eight
million square miles at the South Pole, concerning which little is known. It cannot be told
Whether these desolate fields of ice rest upon land above the ocean level or not.
S :. Divisions.-The water surface of the Earth is divided into five great oceans called
the Pacific, Atlantic, Indian, Antarctic, and Arctic oceans; their areas are as follows:
"P cific ..............about 70,000,000 square miles. Antarctic...........about 8,000,000 square miles.
t ntic............ 35,000,000 Arctic................ 2,000,000
Inlian............. 28,000,000 Inland Seas ..... ... 1,000,000
4. These divisions are all parts of one great ocean. There are no boundaries sep-
aratin,-_ ,ne from another, and excepting the Arctic ocean, not one of them is landlocked.
'. The Pacific ocean has the shape of an oval, bounded on the south by the ice fields
of their South Frigid zone. Its eastern shore forms a long and almost unbroken line. It
enclo.t- the submarine plateau of Oceanica.
t;. The Atlantic ocean is a wide channel between the eastern and western continents.
It.- tw,., shore lines are nearly parallel, the projections of one lying opposite to the indenta-
tions if the other. The shores of the northern part are noted for their many inlets.
S The Indian ocean is an immense gulf, partly enclosed by Africa, Asia, and Aus-
tralia. Its shore line is broken by a number of important peninsulas.
s. ('olor of Ocean Waters.-The color of the ocean varies in different places. Water
more than sixty fathoms deep is blue; shallower water is generally green. The amount of
mineral salts also affects the color of ocean waters. Fresher waters are a pale green, while
tho-l c-.ntaining a greater proportion of salt are dark blue.'
:. In warm latitudes, the ocean waters sometimes glow with a pale light, such as is
no ,tice, I when matches are rubbed in the dark, with moistened fingers. This phenomenon,
known as phosphorescence, is caused by various minute animalcules.
10. The Antarctic and Arctic oceans are comparatively unknown regions, being almost
Scovet.d with ice. In each of these oceans,ice forms to an average depth of seven feet
"during the winter. This amount is about what the sun is capable of melting during the
lILuImner. There are, however, millions of square miles covered with ice which never melts.2
'The Red sea, the Arabian sea, and the Gulf of California are tinged with red ; the waters of the Persian Gulf are
now and then of a greenish hue; while occasionally there are, especially in the Indian ocean, great bodies of water having a
milk-white appearance. These colors are due to the presence of animalcules, or else to microscopic sea weeds.
"2 Late researches render it probable that the ice caps at the poles have formed upon islands, gradually spreading until
a continuous sheet of ice of unknown thickness has accumulated.
82 MONTE/TH'S NEW PHYSICAL GEOGRAPHY.
11. The Bed of the Ocean.-The bed of the ocean consists of extensive plains and
plateaus. Wherever submarine mountain chains occur, they are near some continental
coast. The shores and nearly all shoals are usually strewn with fine sand.
12. Temperature.-The temperature of the ocean varies both with latitude and depth.
Within the tropics, the surface temperature is about 80" F. In the polar regions,it does not
vary much from 28" F.
13. Below the depth of 600 feet,the temperature is not affected by the heat of the sun ;
and except where influenced by
..----.. -- warm ocean currents, it decreases
--uniformly to 35' F., from which it
varies but two or three degrees.
S 14. Where the bed of the ocean
I is not affected by waves or currents,
.. it is covered with ooze, a substance(
Sn consisting of the shells, skeletons,
Sand the insoluble parts of minute
S, rl sea organisms. The ooze covers the
S, bed of the ocean in many places to a
SI great depth.
15. Mineral Salts.-Ocean wa-
-a-- ters contain an average of 3.4 per
cent. of mineral substances, of which
common salt is the chief. The fol-
= lowing table shows the composition
Sof the mineral salts in every 1,00(0
parts of sea water.
SSodium chloride (Salt) ..............27.0
Potassium and Magnesium chlorides.. 5.8
Magnesium and Lime sulphates...... 2 1
J Lime carbonate..................... .1
4 0Is. Iodine, Bromine, and other substances. 3.0
16. The percentage of mini-
The Frozen Zone. eral salts varies in different local-
"ities. In parts of the Arctic ocean,
the salt is almost imperceptible. In the Baltic sea, the water contains but two per cent.,
while in the Red Sea, which lies under a tropical sun, there are 4.3 parts of salt in every
100 of water.
17. Additional supplies of mineral salts are constantly conveyed by the waters of rivers
which, flowing into the sea, deposit there the mineral salts which they have dissolved from
the soil. These salts, therefore, accumulate in the ocean, and mostly remain dissolved. The
carbonate of lime, however, is appropriated about as rapidly as it is supplied, by shell-fish
and other sea animals whose skeletons are composed of that substance.'
i The chalk cliffs of England, much of the limestone of the Mississippi valley,and the coral reefs, have all been formed,
in this manner. Fresh river waters contain salt and carbonate of lime in about equal proportions. In ocean waters, how
ever, there are 270 parts of salt to 1 part of carbonate of lime.
OCEAN WATERS. 83
CONTOUR MAP, SHOWING PROPORTIONATE HEIGHTS OF LAND AND DEPTHS OF WATER.
l.V_ l .. 1" .... --"- -..- --*z -Y .... .. ------
I
.. .... S ,I J.
I 'iIIN N "-
.1 v .1 : r i 1 ," s 1 I r 1 i j: _L ( .! .v
I I I
-, i.--, ,--. ,It. ,.,r- _-,---_ _,,i i ..,,I. l -
Depth in fathoms: under 1000 10 1 2000 1 2000-3000 i 3000 and below
18. Depth.-The average depth of the ocean is about 16,000 feet. Whenever deeper
soundings are met with, the area over which they extend is not a large one; and except along
lie shores of continents,the variations in depth are slight.'
19. The depth of the Atlantic varies in different parts; near the western side it
ik 19,000 feet. Between the two continents, there is a well-defined, submarine highland
known as the "telegraphic plateau," on which the water is about 10,000 feet deep.
20. Along the American coast,the bed of the Atlantic consists of several well-defined
terraces. The first of these is about 100 miles in width, having an average depth of less
than 1,000 feet. At the edge of the terrace,the bed descends almost precipitously to a depth
.,f 9,000 feet. It then gradually descends to about 16,000 feet.
21. The depth of the Pacific and Indian oceans is the same as that of the Atlantic
-16,000 feet. The soundings made in the Arctic ocean indicate a very slight depth; those
,-f the Antarctic are much greater.
I By measuring the breadth, height, and velocity of waves, mathematicians are able to determine the average depth
.f the ocean. In late years,the soundings made with steel wire confirm the calculated depths.
'-' This plateau extends from the Azores to Iceland, and divides the bed of the north Atlantic into two valleys. The
l,.;pth of water on the plateau nowhere exceeds 12,000 feet, and is generally about 9,000 feet. The depth of the eastern valley
'tries from 12,000 to 15,000 feet, and has been traced as far south as the Cape of Good Hope. The western valley has a more
,naeven surface and contains a greater depth of water.
84 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
600 2,4UU 9,000 14,000 9,000 14,400 12,000 6,000
Section of the Atlantic Ocean between Newfoundland and Ireland. The figures show the depth in feet.
22. Inland seas and land-locked waters are always shallow. The Gulf of Mexico and
the Mediterranean sea vary in depth from 7,000 to 10,000 feet. The Red Sea is about 3,000
feet deep; the Baltic and North seas, about 600 feet. The depth of Bering Strait does not
exceed 150 feet.
23. The deepest soundings have been made off the eastern coasts of the continents.
East of the Kurile islands,a sounding of 27,930 feet, and southeast of Newfoundland,one of
27,480 feet,have been recorded. Deeper soundings than these have been reported, but they
are not considered trustworthy.1
24. Waves.-The surface of the ocean is never at rest. Even when it is not lashed
into billows by the wind, it is constantly heaving in long, gentle swells.
25. Waves are caused usually by the wind. They consist of the alternate rising and
falling of successive ridges of water. In deep water, although the wave moves forward, the
water does not; its only motion is the rising and falling.
26. This is apparent when the wind blows over a field of grain. Each stalk bends
before the gust, but immediately straightens, while an instant later, the grain just ahead
bends and straightens. Thus the wave passes over the field.
27. In shallow water, however, the motion of the wave at its lower part is retarded
by friction against the bottom. This causes the top of the wave to comb or roll forward and
break into foam.
28. The size of a wave de-
Sw pends somewhat on the depth of the
water. No large waves form in
water less than 200 feet deep.
29. In deep seas, during a
fair breeze, the waves are about six
feet in height from trough to crest,
and sixty in breadth. Waves of this
.size have an average velocity of nine
._ _- miles an hour ; during a severe gale,
"* ;' the velocity of waves sometimes ex-
Storm Waves. ceeds twenty-five miles per hour.
30. During a severe gale, the top of a wave moves faster than its lower part. In con-
sequence, the waves break and the sea is covered with white-caps, or, in very severe storms,
is lashed into foam.
I These soundings are as reported by Commodore George E. Belknap, when commander of the United States steamer
"Tuscarora." Prior to the adoption of steel wire, rope was used for deep sea soundings. Soundings made in this manner
are now considered wholly untrustworthy. By the late methods, not only are specimens of the bottom secured, but the
temperature at any depth may also be registered.
0 CEAN WATERS. 85
31. The waves do not reach their greatest height until the storm lulls. In deep water,
waves of forty, fifty, and even sixty feet in height have been observed. The breadth of
-such large waves sometimes exceeds four hundred feet.
32. Force of Waves.-The force with which waves beat against the shore is almost
beyond belief. A wave moving with ordinary velocity strikes a blow of 610 pounds per
square foot; but in severe storms, the striking force often exceeds 6,000 pounds upon every
.square foot of surface.
33. The lighthouse on Minot's ledge, near Boston, has been thrice destroyed by storms,
the last time, in 1857. Although it was built of solid iron piles ten inches in diameter, the
combined force of wind and wave swept it away. Not a vestige of the structure has ever
been found.
34. The form of the New England coast is very largely the work of waves. These wear
away the softer rock and the tides carry off the debris. The reefs and rocky islands along
the shores are the remnants of former coast lines.
WHAT HAS BEEN TAUGHT IN CHAPTER XIII.
Three-fifths of the ocean cacters lie south. riand The surface of the ocean is never at rest, but
the remainder north of the Equator. is conastaidly tossed with ewaces or gentle swells.
It is inot definitely 'known tchether the reIions Watres are the alternate rising and falling of
,about the poles are a1end, or water, h, ( lll. successive ridges of cater upon the surface of
The pacificc is the hlarest ocean, being about the sea.
t'iie the size of the Atl(antic, and mnar/y! is larg The ware has a progressive iLmotion, but the
as the remaining for, divisions together. cater ha.s not.
Ini the Arctic ocean, ice forms to and arera(!ge The height of the wave, usually about ole-
thickness of seven feet dutrinir the trinter, andl tentl its breadth, depends chiefly on the depth
imuc h of this ice remains throughout the year. of water.
The bed of the ocean, is diversified with pla- With a fair breeze, deep water rwaes are about
feaus an plains, i feet broad a sir.rt et box feet highl. Their velocity
The best known submarine plateau is il. the is eight or nine miles per hour.
Atlantic ocean, miditay between the eastern rnd The rveloity of storm, waves sometimes exceeds
western conitinendts. twentyit miles an hour.
The average depth of the larger oceans is The breaking of wares occurs wherever the
about 16,000 feet, or three miles. crest of the wave moves faster than, the lower
The depth of land-locked oceans and inland part.
seas is never great, and seldom exceeds 3,000 The waves run highest at the lulling of
feet. the storm.. Then they are sometimes sixty feet
The dwaterof the ocean, contains various )ini- inL height and four or five hundred feet in
-eral salts in solution, the principal of which is breadth.
conomton salt. The force with which 'a wave strikes varies
The amnouint of salt varies front tiro-tenths from 600 ponds to the square foot in ordinary
per cent. in the polar oceans to four and three- weather, to 6.000 pounds to the square foot dur-
tenths per cent. in the Red Sea. indg severe storms.
86 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
too 20 A P T ^ K X40 1
S1 100 1201 140 180 18 160 140 120 100 80- >60 40 80 80 40 0
A TIr c ? Tis o o 0 R I01 R
NortI East Cape SPIT EN
JNEW SIBER IAN IN*! 1 "? \,;AM lf f V Nor: cf
a ,,I hL a i
71.- II1'I-4-*r*8 I
.I '. '-
I Y 11 -[
___r ___ I
CLART OF O-TIDAL LINEs.
c '
'I. M '.,I.n of Ocean Wa ters.-There are two movements of ocean .ate
i' -- f '- ... _- -, 7. ._ .. .. -- -
2. Tid are immense wavs in md- ae a t t e ft in
The riue insin the art s the position n d the fadirectio n f the e "e of th e Th e period s of greatest
eltat the dietion dep io re w as "l o w water, respetiely; that of the cessation of the o',
.cur. O "slack ters.- e are two movements of ocr '
i. 'ide" are immense waves which, in mid-ocean, are about three feet in height
3, binn obse v r standing on the sea shor, will notice that the level of the wate
is not always the same. Feor six hours, it ranches higher and higher upon the beach.
Then it ceases to rise; and after a few moments, begins to recede. It continues to fall
for six hours, when the waters, after emaining stationary for a few moments, again
begin to, rise.1
1 The rising of the water is called the "flood," and the tallingr, the "ebb of tlhu tide. The periods of greatest.
elevation and depression are known as high water" and "low water," respectively; that of thle cessation of the
current, "slack water."
TIDE S. 87
4. The cause of this rising and falling of water is ascribed to the attraction which
the sun and moon exert upon the waters of the Earth.
>-'. Gravitation.-Both the sun and the moon attract the Earth. But while the crust
of the Earth, being rigid, does not noticeably bend, the water is drawn in an elongated
or lemon-shaped form, on account of which it appears to be massed toward the attracting
bodies, as you see in the diagram below.
6. High water does not occur when the moon is directly over-
head, but several hours afterward. In other words, the tide-waves,
owing to friction against the bottom of the ocean, cannot quite
keel pace with
the moon, and
therefore lag
SSUN M behind.
7. The tide-
waves are high-
SMoon in Conjunction. or between the Earth and Sun. est in the trop-
ics, and, except
where the shores of continents cause local irregularities, their height
"diminishes in the direction of the poles.
8. Not only is the water drawn into an ovoid form, but the Earth, also, is pulled
towards the moon. This, in effect, gives the appearance of two waves, one on each side
of the Earth.'
9. Moon in Conjunction.-When the sun and moon have the relative position shown
in the accompanying diagram, it is evident that their combined attraction will produce a
tide-wave, having a much greater height than the attraction of either body alone. In
this position, the moon is said to be in conjunction.
10. Moon in Opposition.-Even though the sun and the
moon are on opposite sides of the Earth, their combined
attraction being in the same line, forms a tide-wave as high
SUN EARTH 20 M
Moon in Opposition, or on the side of the Earth furthest from the Sun.
as though both were on the same side. When the moon
is on the side of the Earth furthest from the sun, as you
.see in the diagram, it is said to be in opposition.
SThis theory of the formation of the tide-wave on the opposite side of the Earth is not accepted by all
scholars.
88 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
11. Moon in Quadrature.-But if the moon is in the position shown in the fol-
lowing diagram, the sun and the moon exert their attractive force, each in a different
direction. In this position,the moon is said to be in quadrature.
12. Four tide-waves a day will take place at such times-two formed by the
sun, so slight as to be hard-
ly noticeable, and two by
Cio IJ. the moon, each of which is
smaller than when both the
"sun and the moon exert a
combined attraction.
SUN EARTH 13. The tide-wave formed
Sby the sun, however, is a
few inches only in height.
In using the term "tide-
Moon in Quadrature. wave," the wave caused by
the moon is always meant.
14. Spring and Neap Tides.-Tides occurring at new and
at full moon-or when the moon is either in opposition or in
conjunction-are called spring tides; those occurring when the moon is in quadrature
are neap tides.
15. Course of the Wave.-The two tide-waves thus formed on opposite sides of the
Earth, accompany the moon and pass around the Earth, each in about twenty-eight days.
But while the two waves are journeying around the Earth, the latter is turning in the same
direction upon its axis every twenty-four hours.
16. Therefore, instead of two tides a month, there are two tides a day. Each day, the
tide is at flood-height about fifty minutes later than on the preceding day.'
17. Effect of Land Masses. -In the foregoing description, it has been assumed
that the surface of the Earth is evenly covered with water. The motion and direction
of the tide-waves are greatly modified by the continents. Especially is this the case in the
northern hemisphere, for here the actual tide conforms but slightly to the theoretical.
18. The tides, instead of having a uniform height of two and one-half or three feet.
as in mid-ocean, are in the North Temperate zone about four feet, although they sometimes
exceed sixty feet.
19. Local High Tides.-In the Bay of Fundy, the tide rises to a height of from fifty
to eighty feet. The reason for this excessively high tide is the shape of the coast, and its
position with respect to the direction of the wave.
20. By looking at the map, you will notice that the tide-wave of the northern Atlantic
travels in a northerly direction. The coast of Nova Scotia and the shores of the Bay of
Fundy have the shape of a A, which faces the south.
S The pupil must bear in mind that the two tide-waves with reference to the moon are stationary-that is, they revolve
around the Earth just as though they were fastened to the moon. The daily tides are caused by the Earth turning on
its axis within the tide-waves. Consequently, an observer overtakes and passes the two waves daily.
TIDE S. 89
21. Into this bay, the tide-wave rushes with a terrific roar, and as the water cannot
spread out, it must rise all the higher. In many estuaries, the bore or egre thus formed
is a wave twenty or thirty feet in height, moving with a velocity of fifteen miles
an hour.
22. All V-shaped bays and estuaries which face the tide-wave have very high tides.
At the mouth of the Hoogly, one of the branches of the Ganges river, and in various inlets
of the Indian Ocean, the tide often rises to a height of forty feet or more.'
23. Inland seas do not usually have a noticeable tide, though there are a few remark-
able exceptions. Thus, while the tide of the Mediterranean is hardly perceptible, that of
the Adriatic (ad-re-at'ic) is between one and two feet in height. The tides of the Red Sea
are often six feet in height.
24. This difference in the tide-level is especially great on the shores of the isthmus
of Panama. Here,the tide of the Atlantic ocean is scarcely apparent; that of the Pacific
is between twenty-five and thirty feet.
25. The erosive power of tides is very great. By their action, bays are formed, and
channels are quickly cleared of the sediment and debris scoured from the coast shores.
WHAT HAS BEEN TAUGHT IN CHAPTER XIY.
Tides are cwaes about 10.000 miles in, The tides of inland seas are generally small
breadth, and in mid-oceatn about three feet or else imperceptible. Those of the Red Sea are
in height. the highest.
Twoo of these wares occur daily, each h i(ce ligh water occurs fifty minutes later on
requiring about twelce hours in its rise and each succeeding day, because the Earth re-
fall. volves in the same direction that the tide-wave
The cause of the tide-twaces is thought to be travels.
the attractive force of the moon and the sun. The continents greatly modify both the direc-
1When the sunt and the moon are in coanjiun- tion a(nd the height of the tide-,wave.
tion, or in opposition, the tides reach their In the South Pacifie ocean, the tide-wave
height. moves in its normal direction towards the west,
When the stun and the moon are in quadra- or the northwest.
tare, there are four tide-lwaves a day, those In the northern hemisphere, the tide-wcaves
caused by the sunt being but slightly notice- are deflected towards the north.
able. On eastern coasts the height of the tide is
Each tide-wa re travels around the Earth in 'usually from four to six feet.
about twenty-eight days. TI A-shaped estuaries which face the tide,
While these waves keep pace with the moon such as the Bay ofFuandy, the tide often reaches
in its revolution, the Earth turning once a a height of fifty feet or more.
day on, its axis, overtakes a tide-wave about The highest tides are on the eastern and
every twelve hours. southeastern coasts of the continents.
SThe observations taken by Lt. Greely in Kane Sea and Smith Sound demonstrate that in those localities the tide.
wave comes from the north.
180 160 140 Longituae est from rreenwich 20 0 90 40 Tongitude Eastfrom Greenwich 100 120 140 160 180 160
S FRANZ JOSEF LAND
T' 0
,... .1|
"i1 ; \ -- '
t- r
SI
20 I i .-
'- -- ... -- .-. '.. ,. i o .
,I; I- V---, i ; "
I. ,."- .. ..; i -
..,''" l i- .' :- ,- .--- ..-"' -. .- :- -- -- ,
I T .I 1 -- --- '' ... -i
S __.. .. ... _'___- _,___ ; __ _, ____ -_.__ ,_ -_.___ _L ... .. ..... 1_.___|
Chart of Ocean Currents.
Compiled from the U. S. ad British Charts.
,,'~~~ ...I ... _.,_;. ..
OCEAN CURRENT S. 91
C( F APTE _AI I X V.
I0 A N T '1 1L _F N 'U S.
1. Movements o f Ocean
Waters. There are other move-
ments of ocean waters which are
of great importance not only to
mankind, but also to every form of
life upon the Earth. These are cur-
rents or rivers in the ocean itself.
_2. There are currents in all
parts of the ocean, but they are
-i- :more noticeable near the shores of
continents because here their ve-
locity is greatest. Temporary cur-
rents or movements of ocean waters
caused by winds are prevalent in all
parts of the ocean. These irregular
movements are not constant, and
therefore, are not classed among
ocean currents.
:3. The temperature of an
ocean current always differs from
that of the water surrounding it,
and may be either warmer or colder.
4. The color, too, of ocean
currents usually differs from that of
the surrounding water. Sometimes
the contrast is so great and the line
between them so distinct that it
seems as though a transparent par-
tition separated them.
5. Causes. -Various theories
have been advanced to explain the
causes of ocean currents, but many
In the Gulf Stream. of the phenomena are as yet unac-
counted for.
6. Probably the prime cause is the heat of the sun. The temperature of the water in
tropical regions is from 800 to 86 F.. while that of the polar regions varies between 28' and
35" F. If water at 32 which just fills a vessel, be heated to 850, it will expand and a part
-of the water will run over.'
Ocean water breezes at a temperature varying from 27 to 32' F. The temperature depends on the percentage of salt.
92 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
7. This is about what occurs in the ocean. The water in tropical regions is heated, and,
increasing its bulk, flows over the surface toward the poles, while the polar waters being
correspondingly heavier, flow below the surface towards the equator.
8. As the colder water becomes warm, it in turn rises and flows toward the poles,
thus producing a circulation which never ceases.
9. There are many other causes which are powerful aids to the circulation of oceanic
waters. The enormous evaporation in the Torrid zone has a tendency to increase the under-
current of cold water flowing towards the equator.
10. The vast amount of fresh water drained from the great basins surrounding
the Arctic ocean, adds another cause. This water being fresh, is, bulk for bulk, much lighter
than the average ocean water.
11. The rotation of the Earth is likewise sufficient to cause a movement of ocean
waters. Inasmuch as the general direction of the winds results from the heat of the sun and
the rotation of the Earth, it seems probable that the circulation of ocean waters is governed
by the same laws.1
12. The unequal level of the ocean is also an important but comparatively unknown
factor in the circulation of ocean waters. Recent investigations show that at the parallels
of 280, there is an accumulation of water forty feet higher than the normal level of the sea
at the poles, and about five feet higher than the actual level at the equator.
13. The winds have much to do with ocean currents, and they certainly give to them
their direction. Indeed, there are many distinguished scholars who assert these to be the
prime cause of ocean movements.'
14. Classification.-There are two general classes of ocean currents, viz.: warm cur-
rents flowing toward the poles, and cold currents flowing from the polar regions.
15. There are also several large areas within the Calms (see chart of Winds) which are
not disturbed either by ocean currents or by winds. On account of the immense quantities
of sea-weed which have accumulated there, they are known as Sargasso seas.3
16. Direction and Velocity.-Taking into account all causes that form or modify
ocean currents, the general circulation of water is :-In equatorial regions, a steady flow of
water in a westerly direction. In temperate latitudes, a general movement of water to the
eastward.
17. In each case the current north of the equator has a northerly drift, and south of
the equator, a southerly tendency. The average rate of these great equatorial currents is
about 10 miles per day. All other currents are due to these general movements, or are
closely connected with them.
18. The Gulf Stream.--One of the most famous, and certainly the best known ocean
current, is the Gulf Stream. This current is formed by the turning of a portion of the west-
ward equatorial current, along the northern shores of South America.
1 The absorption of certain mineral salts, such as carbonate of lime, by corals, mollusks, and foraminifera, to a limited
degree, affects the specific gravity and thus creates motion.
2 The shores of the continents also modify greatly the direction of ocean currents.
8 These accumulations of sea-weed have been considered by many as the result of immense eddies or whirlpools, formed
by ocean currents. Late researches do not strengthen this theory.
OCEAN CURRENTS. .
19. In the Caribbean Sea,O.
it gradually turns northward,
passing around and between the
West Indies. A large part of
this current passes through
Florida Strait, where it receives
a noticeable addition from the
heated waters of the Gulf of
Mexico.
20. The two currents
combined have a velocity of
nearly five miles an hour as they
pass through Florida Strait; but
to the northward, their velocity
gradually decreases. Off Cape
Hatteras, it seldom exceeds two In the Gulf Stream. A Storm Gathering.
miles per hour.'
21. Until this current is opposite Charleston, S. C., its waters reach to the bottom of the
sea, flowing with such force that,in many places,the bed of the sea is swept bare.'
22. In most places, however, the bottom is strewn with minute shells brought from the
Caribbean sea. These serve to mark with accuracy the course of the stream.
23. By the time this current has reached latitude 35'-40',its waters have spread out like
a fan. Not only does it extend northward to the northwestern shores of Europe, but it also
reaches eastward to the strait of Gibraltar.
24. As a surface current having a definite direction, a measurable velocity, and other
distinguishing features, the Gulf Stream cannot be well traced north of latitude 50".
S 25. The warm waters of the Gulf Stream, perhaps combined with those drifted
from the equatorial current, are directly connected with the mild climate of northwestern
and western Europe.
26. Moving in northern latitudes with an almost imperceptible motion, they give heat
to the trade-winds, which, blowing over western and northwestern Europe, temper its cli-
mate, making even the northern shores of the Scandinavian peninsula far milder than the
coast of Nova Scotia, many degrees southward.4
I The Gulf Stream does not flow around the shores of the Gulf of Mexico, as has been until recently supposed; its
direction in Florida Strait is to the northeast in about the same trend as the peninsula of Yucatan.
2 About fifty miles east of Charleston, S. C., and extending north as far as Cape Fear, there is a current setting strongly
to the southwest, even in the face of a hard wind. This current is much dreaded by pilots and masters of vessels. It is
thought to be due to the rising of the Arctic current.
3 The cold current running along the east coast of Greenland is both in width and depth very insignificant, and rests
even near the shore, upon one of warm water produced by the Gulf Stream, Davis Sound and Baffin Bay, on the other hand,
are filled with cold or slightly warmed water to the bottom. Contrary, however, to general belief, the west coast of Greenland
is washed by cold water, while a greatly heated current of water coming from the south, runs along the east coast a distance of
40' to 50' only from the shore."-BARON NORDENSKJOLD. Report of Greenland Expedition.
4 The port of Hammerfest, situated within the Arctic circle, is open to navigation throughout the year.
94 MOVTEITH'S NEW PHYSICAL GEOGRAPHY.
"27. The Kuro Siwo.-The most important current of the Pacific ocean is the Kuro Siwo
or Japan current, a branch of the equatorial, flowing northward along the east coast of Asia.
This current is not only a much smaller one than the Gulf Stream, but it is also a much
colder current.1
28. In winter, when the northeast monsoons are strong, the Kuro Siwo is scarcely
noticeable farther north than the southern limit of the Japan islands, and often it is arrested
for days at a time by adverse winds.
29. In summer, with the coming of the southwest monsoon, the Kuro Siwo puts forth
its strength and passes the northern extremity of the Japan islands before turning east-
ward.
30. During all seasons of the year, however, the Kuro Siwo obeys the laws of ocean cur-
rents and turns eastward, where its waters, spreading out, are pushed towards the American
continent.2
31. Cold Currents.-The most important cold currents come from the Arctic ocean, one
through Baffin Bay, and another to the eastward of Greenland. These unite off the extremity
of Greenland, and continue as surface currents, as far south as Newfoundland.
32. The cold current east of Greenland is, according to Baron Nordenskjold, a surface
current flowing on the top of a warm under current. South of Newfoundland,it becomes an
under current.
33. The Arctic currents meet the Gulf Stream at the surface off the coast of Labrador.
The moisture-laden atmosphere is here cooled to such an extent that dense fogs constantly
hover over this region.
34. The icebergs brought down by the Arctic current, on reaching the latitude where
these currents meet, drift helplessly about until they melt.3
35. The cold currents of the Antarctic ocean consist of a general drift of the waters
towards the northeast, rather than well-defined currents.
36. Currents of the Indian Ocean.-The most important current of the Indian
ocean is the Malabar. It is formed by the northward bending of the equatorial current. The
Malabar, like the Kuro Siwo, is greatly modified by the monsoons.4
37. Other Currents.-There are several other well-defined ocean currents, especially
in the southern hemisphere, of which the Brazilian and the Mozambique are perhaps the
most important.
38. Economy.-Each of these currents, whether warm or cold, has an important in-
fluence upon that part of the continent along whose shores it flows.
I In latitude 35', the average winter temperature of its waters is 63 F.; the average summer temperature is
nearly 700 F.
2 No branch of the Kuro Siwo enters Bering Sea; on the contrary, the only current of Bering Sea is a movement of
water southward through the strait.
8 A cold current has been discovered by Prof. Davidson,off the coast of California, lying close to the shore. Its origin
and destination are as yet unknown.
4 There is a surface current entering, and an undercurrent flowing out of the Red Sea through the strait of Bab el
Mandeb. This is said to be owing to the great evaporation going on in this body of water. The evaporation from the
surface is sufficient to cause an inflow of water, while the increased specific gravity of the remaining waters, containing
about one-fourth more of mineral salts, would cause an outward flow at the bottom.
OCEAN CURRENTS. 95
39. The influence of the Gulf Stream on northern and western Europe presents a strong
contrast to that of the Arctic current upon Labrador. The latter is an uninhabitable, frozen
waste; the former, the center of the most thickly populated part of the world.
40. Terrific storms follow the track of all warm ocean currents. This is especially true
of the region about the China Sea, and that part of the Atlantic ocean which is east and
southeast of the United States.
41. The exceedingly large rainfall of the southeastern part of the United States,
varying from 70 to 90 inches per year, is owing to the moisture-laden winds of the Gulf
Stream.
42. Thus we may see that the ocean, which at first may appear as a great waste, is an
absolute necessity-to all forms of life upon the Earth. It is the source of all fresh waters;
and by carrying away the intolerable heat of the tropics, it tempers alike the cold and the
warm parts of the Earth.
WHAT HAS BEEN TAUGHT IN CHAPTER XY.
Currents of water exist in all parts of the From the coast of Florida, it takes a north-
ocean. Their temperature differs from that of easterly course reaching to the iorth sea and
the 'waters in which they flow. Tlese movements spreading. along the shores of' western Europe.
are caused ch iv tqi by the heat of the siun. Its velocity along the southeastern coast of the
The water at the Equator is heated to a tern- United States varies between two and one-half
peratare of about SO" F., i while a(t the polar re- and four and one-half IIl es per hoar.
gions, the temperature is often as low as 27 or The Kuro Sico, the most important current
28' F. of the Pacific ocean, is a simnaller and colder cur-
The heathin of equatorial 'waters increases rent than the Gulf Stream.
their bulk and causes a current towards the Its Iorthern, limits are controlled by the mon-
poles. soon wiinids which often wholly check it for days
These 1novements are balanced by cold under- at a timHe.
currents of water flr-t tn fr'om polar regions Its waters are finally distributed alonfs the
towards the Equator. Pacific coast of North America, hose climate
The direction of ocean currents is due chiefly this current is thought to 'modlify.
to the winds, the shores of continents, and the The principal current of the Indlian, ocean is
rotation of the Earth on its aris. the MZlalabar, a branch of the equatorial cur-
Tle general direction of warm ocean cur- rent.
rents is westward in the Torrid zone, and east- The principal cold currents are the Arctic
ward in, the Temperate ones. currents, one flowing south tcard through Baffin
Within the region of calms, there are areas Bay, the other flowing to the eastward of Green-
of undisturbed waters filled with seaweed, which land.
are known as Sargasso seas. A feeble cold current flows out of the Arctic
The direction of cold currents is irregular, occan through Bering Sea.
but always towards the Equator. The warmn ocean currents, jil'iir;ii through
The Gulf Stream, the most important branch the colder regions of the Temperate and Frigid
of the equatorial current, has its origin in the zones, modify their climate by warming the
Caribbean sea. wind s which blow over them.
96 MONTEITH'S NE W PHYSICAL GEOGRAPHY.
CHAPT ER XVI.
THE ATMOSPHERE .AND ITS MIOVIMtNTS.
1. Density.-The atmosphere, or air, is the outer part of the Earth which surrounds
the solid crust. It is extremely light; one cubic foot weighing about one and one fifth
ounces, while a cubic foot of water weighs 62.42 lbs., or about 800 times as much.
2. Height.-The height to which the atmosphere extends above the surface of the
Earth is estimated at from 50 to 200 miles. The weight of a column of air as measured by
the barometer indicates the former height.
3. The great height at which meteors are vaporized, together with the measured height
of the Aurora Borealis-both of which are thought to depend upon the atmosphere-leads
to the belief that it extends at least 200 miles beyond the Earth's surface.
4. Composition.-Air is composed of a number of gases in a state of mixture.
Every 100 parts contain 77.95 of nitrogen, 20.61 of oxygen, 1.40 of aqueous vapor, and
0.04 of carbon dioxide.
5. The amount of water varies greatly, seldom being
the same on two successive days. The amount of carbon
dioxide is likewise variable, being greatest in thickly populated
localities.
6. There are also minute dust particles, the various vapors
and gases constantly rising from the earth, the products of
combustion, and occasionally, traces of meteoric dust.'
7. Physical Properties.-Air is highly elastic, a pressure
of about 15 lbs. per square inch being sufficient to reduce its
bulk one half. It will also expand as the pressure decreases.
8. The Barometer.-The pressure and the weight of the
air are found by means of the barometer, which is shown in
the accompanying figure.
9. The tube which is closed at one end is filled with mercury
and inverted, the open end being placed in a dish of mercury.
The mercury sinks in the tube until the column, if the experi-
Sment be performed at the sea-level, is about thirty inches high.
The Baroneter. 10. The column is held at this height by the pressure
of the air on the surface of the mercury in the dish. In
other words, the air and the mercury exactly balance each other, and, therefore, have
each the same weight.
SThe red sunsets of 1883-4 have been attributed to the latter cause. Certain it is that microscopic analyses of the
air proved the presence of finely divided volcanic matter in great abundance. By Professor Tyndall, the blue color of the
sky is attributed to the presence of minute particles held in the atmosphere.
STHE ATMOSPHERE AND ITS MOVEMENTS. 97
11. By weighing the column of mercury,we at once know the weight of the column
of air which balances it. At the sea level, when the column of mercury is thirty inches
high, the weight on every square inch of surface is 14.7 lbs.
12. Changes of Barometer.-But the column of quicksilver in the barometer tube
is constantly changing in height. Therefore, we know that the thickness and weight of the
layer of air over our heads are constantly changing.
13. If the mercury rises to a height of 30.7 inches, it indicates that a wave of air
"has gathered above us; should it fall to 29.4 inches, it follows that there is a much thin-
ner layer of air overhead.
14. Observations taken in different latitudes at the sea level show that the atmosphere
Does not surround the Earth in a layer of equal thickness, but is distributed, as you may
see in the diagram on page 98.
15. Like the waters of the ocean, the greatest thickness of the atmosphere is in
latitudes 28' to 350. The decrease in thickness towards the poles, although not great, is
nevertheless perceptible.
16. The uneven distribution of the air is shown in the accompanying table, being
the average of many years observations at the sea-level.
Clhristianburg.. Latitude, 5 30' N. 29.92 in. Tripoli ...... ...Latitude, 388 N. 30.21 in.
St. Thomas..... 19 29.94 Florence........ 43 30' 29.99 "
Macao ........... 23 30.03 Dantzic.......... 54 30' 29.92 "
Teneriffe ........ 28 30.08 Reikiavik....... 640 29.61 "
17. Effect of Altitude.-It is also evident that as one ascends above the sea-level the
mercury will fall, because there is less air to balance it. Careful observations show that
this difference is about one-tenth of an inch for every ninety feet.
18. Torricelli's Experiment.-The discovery of this principle was made by Torricelli
(Tor-e-chel'-ee), a pupil of Galileo. The conclusion that the barometric column is sustained
by the pressure of the air,was denied by philosophers of that time.
19. Pascal's Proof.-Pascal (Pas-kahl'), a young French scholar, convinced of the
truth of Torricelli's reasoning, proposed to decide the matter in a practical way. He
measured the height of the mercury at the base of a high mountain, which he immediately
afterward ascended, again measuring the height of the column.
20. The result proved the truth of his theory: the column of quicksilver steadily fell
till he reached the summit of the mountain; and, as he descended, the mercury rose again
"to its former height, thus conclusively proving Torricelli's theory.'
21. The weight or tension of the atmosphere may be readily found by observing the
height of the mercury in the barometer tube. This, we shall see, constantly changes.
Since the time of Pascal and Torricelli many improvements have been made in the form of the barometer, without,
however, deviating in the least from the law established by these scholars.
The following shows the effect of altitude upon the barometric column:-At the level of the sea, the column is
80 inches; at 3.4 miles above the sea,it is 15 inches ; at 6.8 miles, 7.5 inches ; at 10.2 miles, 3.75 inches; at 13.6 miles, 1.87
inches; and at the height of 17.0 miles, .94 inches. In other words, the weight and density of the air are halved for
*-very 3.4 miles above the sea-level. The highest altitude ever reached by a balloonist is about 74 miles. At this height
"the barometer fell to 7 inches. At the present time,the barometer is one of the most useful of all instruments in measuring
the altitude of mountains.
.98 MONTEITH'S NEW PHYSICAL GEOGRAPHY.
22. Movements of the Atmosphere.-Like the ocean, the air is subject to great
disturbances. There are tides, currents, and irregular movements of the atmosphere on a
scale grander even than those of the sea.
23. Winds.-Movements of the atmosphere are called winds. They may be constant
and regular, or they may be irregular. The former comprise those which blow steadily,
with constant force,and in certain known directions, during a fixed period.
24. These winds are usually confined to the ocean and sea coasts. They are known
as trade winds, passage winds, polar winds, monsoons, etc.
25. Cause of Winds.-The heat of the sun, the prime cause of ocean movements, also
causes those of the atmosphere, and the laws which govern one likewise control the other.
26. The general movements of the air, like those of the ocean, originate in the
equatorial regions. Wherever the sun's rays fall vertically on the earth, the air becomes
heated, and therefore, expanded.
27. The heated air, being bulk for bulk lighter than cold air, rises; at the same time,
cold air is pushed in to fill the vacant space.
28. This may be easily illustrated by throw-
ing bits of tissue paper upon a hot stove.
They are at once carried upward by the rising
current of air. To fill the place of this, cold
air is forced in on all sides.
29. Direction of Winds.-If now we ap-
ply the same reasoning to the atmosphere of
the Earth, we shall find that the general
movements are similar.
30. These are chiefly-An upward current in
equatorial regions,which sets toward the poles.1
Currents of air towards the equator to re-
place that which has risen.
Polar currents blowing toward the equator.
31. These laws are greatly modified,not only
by the spinning of the Earth on its axis, but
also by the continental land masses.
32. Effect of the Earth's Rotation.-The
The Circulation of the Atmosphere. rapid motion of the Earth on its axis from
west to east modifies the direction of the
winds blowing toward the equator, so that north of the equator,they blow towards the south-
west, and south of the equator, towards the northwest.
33. Trade Winds.-These winds, on account of their favorable direction to vessels
plying on certain commercial routes, have been named trade winds. They are constant
throughout the year, blowing not only with regularity but also with a uniform velocity.
34. The belt or zone of trade-winds, moves a few degrees northward, during the
summer of the northern hemisphere and southward, during the winter. Their northern
limit in summer is about latitude 240 N. ; in winter, about latitude 5' N.1
SThe upward current is in the latitude where the sun's rays are vertical. 2 Reports of U. S. Hydrographic Office.
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