• TABLE OF CONTENTS
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 Front Cover
 The geology of St. Lucia
 Geological survey of Grenada
 Bibliography






Group Title: The geology of St. Lucia : Geological survey of Grenada
Title: The geology of St. Lucia
CITATION PAGE IMAGE ZOOMABLE
Full Citation
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Permanent Link: http://ufdc.ufl.edu/UF00054980/00001
 Material Information
Title: The geology of St. Lucia Geological survey of Grenada
Physical Description: 16 leaves : ; 33 cm.
Language: English
Creator: Earle, Kenneth W
Earle, Kenneth W
Publisher: s.n.
Place of Publication: S.l
Publication Date: 1923?]
 Subjects
Subject: Geology -- Saint Lucia   ( lcsh )
Geology -- Grenada   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references.
Statement of Responsibility: K.W. Earle.
General Note: Caption title.
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Bibliographic ID: UF00054980
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
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Resource Identifier: oclc - 52906802

Table of Contents
    Front Cover
        Front Cover
    The geology of St. Lucia
        Page 1
        Topographical
            Page 1
        Geological
            Page 2
            Page 3
            Page 4
        Economic
            Page 5
    Geological survey of Grenada
        Page 6
        Topographical
            Page 6
        Geological
            Page 7
            Page 8
            Page 9
            Page 10
        Economic
            Page 11
            Page 12
            Page 13
            Page 14
    Bibliography
        Page 15
        Page 16
Full Text









A


TH BOLO'Y 07 ST. LUIA
LY *
Ki. .7. .2L


GOVERNMENT GEOLOGIST
SWINDWARD ISLANDS






THE GEOLOGY OF ST. LUCIA

K. W. EARLE.



A. Topographical

St. Lucia th- most northerly of the Windward Islands,
and the largest of all the Windward ard Leeward Is !nds with the
exception of Dominica is situated ir Lat. 140N -nd Long. 62-W.
It is separated from Martinique on the north by a channel about
20 miles wide, and from St. Vincent ,n the south oy a channel about
25 miles wide, It has a maximum length of 25 miles and a maximum
width of 12 miles.

Topographically and geologically it is almost an exact
replica of Dominica and most of the geological part of my report
on the latter island can be equally applied to St. Lucia. The
topographic differences between St. Lucia and Dominica are those
rather of size than anything else. In St. Lucia tho mountains are
more "hummocky" and do not reach the same altitude of those of
Dominica, the rivers are consequently smaller and have less erosive
power, and do not, as a general rules present the same gorge-like
characters as those in Do.ilnica. Only on the leeward coast between
Anse-la-Raye and Soufriere is there any development of canyon-like
gorges and this is t i orly area aloLg which a motor road has not
yet been engineered. Unlike Dominice indeed, there are in St.
Lucia several wide, fertile, almost flat valleys unday extensive
sugar cultivation tpys are at D'Ennery on the Windward and Cul-
de-Sac and Roseau on the leeward coasts.

The north-.n and southern ends of the island are much
less mountainous, c sisting of the rain-wash, ash etc., swept
down from the contra.. ranges. The southern (Choiseul to Vieux-
Fort) part of the island is much more like St. Kitts, consisting
of sandy friable soi.s forming a gentle slope from 1000' to sea
level and traversed by V-shaped ghauts or valleys. The extreme
southeastern end of 'he island consist.3 of an absolutely flat plain
three or four miles in extent but little above sea level. This
is terminated by a bold rugged promontory 750' high and known as
Moule-a-Chique on which the lighthouse is situated.

As would be expected, the windward coast is much more
indented than the leeward and erosion has produced a number of
small islets such as Bouche I., D'Enzery I., Praslin I., and Maria
I. On the North West are also the srall islands known as Pigeon
I. and R.t Island.

The mountainous area consists essentially of one central
range giving off lateral ridges towares the sea. There are how-
ever, numerous subsidiary ranges and peaks not marked relation
to the central range, so that the aspect of the island seen from
the Morne (Castries) or t:. Lighthouse (Moule-a-Chique) presents
rather a "hummocky" series of detached peaks and ridges than that
of one maturely deve? ped mountain range. This is lue to the fact
that the volcanic fcci were situated at numerous points within
the island and not confined to one continuous line of weakness.
The highest mountains are Mt. Gimie (3145'), Piton Canaries (3012'),
Mt. Parasol (2011'), .It. Tabac (2270').Mt. Belvedere (2198')
Morne Grand Magasin .2417') and the Gros and Petit Piton (2619'
and 2461') in the s- thern and soufriere region, as well as The
Soiciere (2210') an. Piton Flore (1850') in the northern area.


By/2






THE GEOLOGY OF ST. LUCIA

K. W. EARLE.



A. Topographical

St. Lucia th- most northerly of the Windward Islands,
and the largest of all the Windward ard Leeward Is !nds with the
exception of Dominica is situated ir Lat. 140N -nd Long. 62-W.
It is separated from Martinique on the north by a channel about
20 miles wide, and from St. Vincent ,n the south oy a channel about
25 miles wide, It has a maximum length of 25 miles and a maximum
width of 12 miles.

Topographically and geologically it is almost an exact
replica of Dominica and most of the geological part of my report
on the latter island can be equally applied to St. Lucia. The
topographic differences between St. Lucia and Dominica are those
rather of size than anything else. In St. Lucia tho mountains are
more "hummocky" and do not reach the same altitude of those of
Dominica, the rivers are consequently smaller and have less erosive
power, and do not, as a general rules present the same gorge-like
characters as those in Do.ilnica. Only on the leeward coast between
Anse-la-Raye and Soufriere is there any development of canyon-like
gorges and this is t i orly area aloLg which a motor road has not
yet been engineered. Unlike Dominice indeed, there are in St.
Lucia several wide, fertile, almost flat valleys unday extensive
sugar cultivation tpys are at D'Ennery on the Windward and Cul-
de-Sac and Roseau on the leeward coasts.

The north-.n and southern ends of the island are much
less mountainous, c sisting of the rain-wash, ash etc., swept
down from the contra.. ranges. The southern (Choiseul to Vieux-
Fort) part of the island is much more like St. Kitts, consisting
of sandy friable soi.s forming a gentle slope from 1000' to sea
level and traversed by V-shaped ghauts or valleys. The extreme
southeastern end of 'he island consist.3 of an absolutely flat plain
three or four miles in extent but little above sea level. This
is terminated by a bold rugged promontory 750' high and known as
Moule-a-Chique on which the lighthouse is situated.

As would be expected, the windward coast is much more
indented than the leeward and erosion has produced a number of
small islets such as Bouche I., D'Enzery I., Praslin I., and Maria
I. On the North West are also the srall islands known as Pigeon
I. and R.t Island.

The mountainous area consists essentially of one central
range giving off lateral ridges towares the sea. There are how-
ever, numerous subsidiary ranges and peaks not marked relation
to the central range, so that the aspect of the island seen from
the Morne (Castries) or t:. Lighthouse (Moule-a-Chique) presents
rather a "hummocky" series of detached peaks and ridges than that
of one maturely deve? ped mountain range. This is lue to the fact
that the volcanic fcci were situated at numerous points within
the island and not confined to one continuous line of weakness.
The highest mountains are Mt. Gimie (3145'), Piton Canaries (3012'),
Mt. Parasol (2011'), .It. Tabac (2270').Mt. Belvedere (2198')
Morne Grand Magasin .2417') and the Gros and Petit Piton (2619'
and 2461') in the s- thern and soufriere region, as well as The
Soiciere (2210') an. Piton Flore (1850') in the northern area.


By/2








By far the most imposing of these and worthy of more de-
tailed description are the Gros and Petit Piton, These peaks are
well known to all travellers and ari probably the most imposing of
all the West Indian mountains. The- owe their magnificence to their
proximity ~ to the sea, f-:om which th y rise in towering twin peaks.
The more southerly or Cros Piton is the l.ss imw.osing of the two as
its slo.ep are not sn steep; the PLtit Pit&n .-!-ich rises a veri-
table Matterhorn -o a height of 2461 ft and has an apical angle
of not more than 70 was for long considered iuncaleable owing to
its precipitous cliff sides; in the last 20 yea:s, however, it has
been scaled on several o-casions. Vi.ewed from the southern side it
is seen to b. split into twin peaks by a N.W. S.E. fissureeBetween
the Gros and Petit Piton is a sandy bay and a ser:.-circular amphi-
theatre hemmed in on the landward side by a contiL-nous ridge of
hills nowhere much exceeding 1000 ft in height. We have here in
fact, a well define extinct crater the western siie of which has
been carried away b,; the sea. I

There i. 'a St, Lucia, as in most of the other islands of
the Lesser Antilles an active Soufri.re. This is situated in a
high mour.tain valley above the Village of Soufriej~e. Apart from the
boiling lake of Domrr"ica it is probably the most ir'8psing of all
the Soufrieres and c-,nsi ;ts of a number of small ,auldrons throwing
up boiling water to height of several feet accoi.pa -ied by dense
volumes of steam. C.e such lake which was devoid of vater at the
time of the writers visi-c was throwing up black nmd.o The sulphur
charged waters are 'eputed to be good for rheumiatie complaints and
a bath has been buiL-: over one of the smaller war.- springs.

The rainfall -f St. Lucia 's high and the numerous rivers
though not fc:?midable ilJ dry weather. rise tremendously and cause
much damage at times &1 heavy rain.

Castries the Capital i situated on a magnificent
land-locked harbour at the N.W. end .,f the island, This is, in fact,
the only harbour in the West Indies *except Deme aQra) where the
steamer co-les alongside to the wharf and for this reason the island
has in the past attained much importance as a coaling station.
Soufriere end Vieux-Fcrt on the Leeward side of the island also have
safe and sheltered anc-orages the former under the lee of the Petit
Piton before described and other sa'e anchorages for small sloops
occur; on the Windward s de of the island no really safe anchorages
exist except for one or two bays which are hemmed Jin by coral reefs
and on that account "lade difficult of entry to all but the smallest
boats.

Feciliti,; for transport are much better in St. Lucia than
in DominLca, but o.l1 leave room for improvement. Of late years
a through mctor road has been made ove-' the central iange of mountains
connecting Castries vith D'Ennery while from D'Ernery a road extends
all round the eastez and southern coast through Miccad, Vieux-Port
and Choiseul to Soufrier.. Communication between jVi-ux-Fort,
Soufriere and Castri s is maintained by motor bus an'l coastal motor
boat ser ice, A goo rosa also extends from Castries to Gros Islet
at the n'.rth end of he island, but the~r' is no road on the windward
coast between Gros .et and D'Ennery.



B. Geological

Geologically, St. Lucia is a reproduction of Dominica,
or rather a combinatica of Dominica -ad St. Kitti,


The/3








"The isli.d may be considered as a ccni~~sed amorphous
mass of igneous material, without any definite st-:.*tu'al arrange-
ment and its rocks, with the exception of the coialline limestone
found in th. neighb urhood of Soufriere, are al i-7 gneous urigint
Tiee rocs are eithW. crystalline in t ;-nature of '.aps, exhibit- '
ing much variety o- structure, or unc:-ystalline composed of volcanic
ashes constituting tuffs. Of the former many resemble basalt
and greenstcne while some are an approach to grar-ite and syenite.
The mountainF: are made up of volcanmi conglomerate and basalt
rocks of all sorts (-orphyrites, an'.esites, pumiceous bedded tuffs)
phonolitic and schistose masses, feastones, lavas and such like
are found. These rocks are Tertiary and Post-Tertiary" (John
T. Rea, Curveyor, R.E. Establishment, 1897, in "Hand Book" of St.
Lucia 1 ;98).

This, if we take exception to the terms "Granite", "Syenite"
"Schistose masses" and i.iterpret the old rock names in terms of
modern nomenclature, represents and accurate description of the
Geology of Ste Lucia.

There is probacl y an earlier igneous fc'undation of
volcanic rocks, as in the other Volc.nic Islands o- the Lesser
Antilles, but those are almost everywhere obscure'- by the later
pyroclastic ejectam.nta. The only places indeed round the coast
where massive lava -as been seen in eitu are at Cap, Vigie and
Toc (Castries), T;. 'ielle Point (between Anse-la-Raye and Castries),
at the Gros and Pel. t Piton, at Laborie and at Moule-a-Chique
(Vieux-Fort).

These roc .; m'", be described petrologicallzr as andesites
and basalts, the ferrcmajnesian mineral, where debernrinable, being
generally augite or iypersthene.

The rocks >ften consist of two generations of felspar
without marked fern nagnesian minerals, while occasionally olivine
is sufficiently abundant to constitute the rock a6 an olivine
basalt.

In the field these rocks f equently show splendid
spheroidal weathering and a parallel cleavage mistaken for bedding
by certain local residents anxious to prove the presence of
petroliferous strata in the island.

At Vigie ani Moule-a-Chique there are found black augite
basalts, conspicuous for the abundance of their amygdales which
are drawn out lengthways in the direction of flow and lined with
dome ? zeoI.itic mineral.

From Dauphin Beach a rock was collected approximating
to a quartzite or a quartz schist, aid from D'Enn;ry Beach a horn-
blende diorite: beach boulders are, however always misleading
as there is a possi- ilit; that they have been brought from else-
where (e.g. Trinida ) as ballast in sloops.

These C:u -'ritic and basaltic rocks are often extensively
decomposed in the d. 'cct.on of Talc o0 Kaolin; the andesitic rock
being worked in thr Arovernment Quarry (Castries Harr.our) is character-
ised by about 5.ff 5 granular pyrites.

The rocks composing the Gros and Petit Piton, are some-
what different in character, being more acid than is generally
the rule. In hand specimen they are holocrystalline, consisting
of small crystalls 'J transparent pinkish quartz aii-f elongate
Ferromagnesian mi-'zrals in a microcrystalline grey-white ground
mass*


Under/4






-4-


Jnder the microscope the quartz is co.l picuous in large
rounded cr:/stals traversed by irregular iron-bearing cracks. The
felspar pher:-crysts are large, square or polygonal, markedly zoned
and twined -o correspon: to andesine or possibl,- labradorite. The
ferromagnesian minerals r e augite ard hypersther.:, Magnetite
and heamatite occur in t.ie groundmasL with abundant granular quartz.

This reck seem: to have been previously described as a sani-
dine trachyte. I .- re net positively identified sanidine in my
slides end the ab.-L .ance of quartz would appear to refer it more
to the Quartz Andeu tes or Dacites.

Softer ( ,lightly decomposed) varieties of such rock
are known locally a- "Pierre Taille' and used as f-.restone and free
stone.

The latter volcanic accumulations do noit call for lengthy
description as they are paralleled in Dc-minica and elsewhere .
They consist of ash .3, grits, volcanic agglomerate:; and breccias.
The constituent boulaers are generally angular aan. often reach a
large size. These ashes and tuffs h .ve almost irnariably a nodial
slope from the mountains as is seen -n the cliff sections. The
only point where anytaiig approach ;- true beddel sediments occurs
is in a small roadside exposure betvw-en the race course and Choc,
where there are fine gr:ined ashes e~id mudstones with a conchoidal
fracture -.ipping 3CP 8,E These are exactly paralleled by similar
rocks ir Grenada. No fossils are se.n and they probably represent
temporary subaqueous terrestrial (or freshwater) deposits accumu-
lated during a pause in the volcanic activity. There is nothing
to indicate that thcL e not Pleistocene age,

In the neighbourhood of Vid3 Boutielle, there are broad
coastal sweeps of much ye'.lower tuff, resembling somewhat the lower
tuffs of Antigua. On cloje examination these pro-i. to be fine
volcanic breccias, consisting of lapilli or angular fragments of
grey pumiceous to yellow kaolinised .lava in a finer grey matrix
The texture of this .eposit varies very much and is possible to
collect a hand spec& -en knowing gradations from a fine angular breccit
to a fine banded ': : or silt. The d'p is as usual radial to the
mountains and the rc ;ks are not true stratified subaqueous deposits.
Very interesting i -*he occurrence in these rocks (although I did
not collect any my-l.f in situ) of petrified wocd, a feature which
is to be paralleled v:.th the tuffs and Cassada Garde:. Gravels of
Antigua.

Small quantities of crystallir.n quartz, :jacper and chalce-
dony occur in the p;.:'oclastic rocks. -The interior T:ountain area
of St. Lucia, where -;he rainfall is high, shows no surface rock
but red clay to a considerable depth in which occur r residual bould-
ers of andesitic or basaltic rock. 1. noticeable exception to this
rule is the h:.ghland above Soufriere Village, where there is no
extensive development o2 red clay.

The only unqu-.stionably ma ,ine deposit is a small pocket
of limestone situated az'out 100 15-' above sea level near the
main roI. at Malgretoute (Soufriere)~ In this t-ie only common
fossil is the usual Orbicella, and th3re is litt_-e doubt that the
deposit is a raised coral limestone c.' Pleistocene age. (cf similar
deposits in Dominica).

Ap;t from the Soufriere mentioned abo-e there are
numerous cold carbonated springss in St. Lucia. These are often
very rich in iron and for'. deposits of travortino in which petrified


cocoa/5






-5-


cocoa leaves etc are preserved. Examples of these are found at
Cul-de-Sac, Leausejour, (Choiseul) Falgretoute, (Soufri.ro), Del
der Flo (D'Ennery) while at Ferrand (Cul-de-Sa-) a similar spring
has given rise to an extensive depo it of pure ,alcium carbonate.

C. Econ .-ic

Oil
inder ordinary circumstances no cuch heading as this
would oc.cu in any geological report on St. Lucia, were it not that
certain local residents have postulated the occurrence of oil in
Barbados and Trinidad as indicative cf the existence of oil in St.
Lucia and misinterpreted the field evidence to fit in with their
theories.

Th3 oil f.eld areas of Triitidad and Barbados ( and indeed
almost every oilfl:.i, throughout the world) consist of stratified
sediments which a.; practically non-existent in St. Lucia, the whole
island being compos, 1 of volcanic roc-s and their pyr-oclastic deriva-
tives which, owing the nature of their eruption and consolidation
sometimes siow a ri ial slope from the mountain ranges, exhibited
in the coast sections as pseudo-stratified bands of material verying
very much in coarser ss from ash tj boulder beds; this grading of
the deposit must no be confused with the 'dip' of a subaqueous
stratified deposit.

The only ild 'indication' of oil cons'.sts of inspissated
petroleum cr pitch ad'he-eing to the :-ocks invariably on the beach,
and never indisputably inland. This phenomenon is repeated in
Dominica, Grenada a," ,' Grenadiner. To the writer's mind it is
indisputably jessam, and its sticky character would incline one to
the belief that it has travelled far and is more likely to be derived
from some submarine outbrop of oil-l-aring sedJinants, east of the
Windwar(. Islands, than from known exposures of Manjack etc., in
Barbados and Trinidac.,

(It is worth putting on record however that there is pre-
served in the British Museum among Flett's specimen immediately
after the St. Vincent eruption of 19C2 a specimen of "Tar exuding
Hot ashes in the Dry river on the south side of the Soufriere". No
suggestion is offered as -o whether this is an ari-ificial occurrence
or whether it is due in some way to -olcanic activity, but in any
case it is no indicr-ion of petroliferous strata).

The film (so-called) 'oily' material seen on the sur-
face water of low i:~ 'ng land merely represents a filra of Iron Oxide
derived from the t~?-uginous clays and decaying vegetation and is
no indication whatevr of petroleum.

Whether ,'-3 volcanic piles of the Windward and Leeward
Islands are built up on I.re-existing land cannot be proved, but
all the evidence sees to indicate that they origi.atled as submarine
volcanoes and were c.ily part overlain by stratified deposits (since
largely denuded) an" i:n i.ny case one w.-uld not recoraend drilling
in the hopes of fir .ng stratified and oil bearing,: sediments below
the pyroclastic rock- forming the present :.iountair. chains.

Miscellaneous
A negligeable amount of irwin pyrites occurs disseminated
through some of the volcanic rocks. A rock of this type from the
Government Quarry Castries Harbour h ts already been referred to.

The decompossi rock known as 'titfr -., as elsewhere used


to/6





r6kEr4At> A1,


-6-


to mix the lime for building purposes. The 'Pierre Taille' (fire-
stone) has already been alluded to.

Lime is obtained from the recent bea..:: coral, and from
an insignificTant exposu-ea of limestone near Sof'zriere.

bulphur has on several occasions been -. rked at the
Soufriers, and at the present time there can be seon the machinery
installed by the American Company wh. unprofitably tried to work
the deposit,

Pottery :- made in small qu..ntities at the neighbourhood
of Choiseul.
One or t.-o river concentrates were examined to see if
traces of gold or .:lver could be discovered. The sample from
Fond St, Jacque (Soufrie2e) consisted chiefly of quartz and fels-
pathic material with limonite, chloritised mica and hypersthene.
No silver platinum cr gold could be detected either here or in the
sample from the Riviere D'Oree. The very pronounced golden tint in
this latter river :-; doubtless due to chloritised r:Lca, which was
identified in the analysis in spite of its rarity in microscopic
sections.

St, Lucia a;pears to be or- of the few West Indian
Islands where there is unlimited wat3r supply at all times of the
year and in view of the simple berthing facilities at Castries,
steamers are often wort to come in a id takes or. s-pplies of fresh
water.
Sgt. T('.reeth W. Earl.e M.Sc., F*I.C.
Govcrrment Geologist to the Wi1dward and
Leeward Islands, SepGt 6th. 1923.


1901 JoW, Spencer.


1901-2 J.W. Spence.


1903


1904

1905


K. von S-e :,r


O',o0 Hove.

. .T Hill


In Press T, Vaugh1_.:i.
and Prof. r...vey




B GEOL B .
[A^> (By .:.


The Geological and Physical Development
of Dominica, with Notes on St. Lucia etc
Q.J.G.S., LVII,
The Windwced and Leeward Islands.
Trans. Canadian Institute.
Zur Kentniss der Inseln St. Lucia,
Monserrat, Nevis c-nA St. Kitts.
Centralblai t fur Min. Geol. and Pal.
Soufriere de Sainte Lucia.
B.G.S.A., Vol. 16.
The Evolution of the Windward Archipeligo.
B.G. SA., XVI.
The Igneous Phenomena of the West Indies*


ICAL SURVEY GRErNAOAi
V. Earle, M.4 *. ::' -So- )


A. TOPOGRAPHICAL

Grenada, th6 most southerly of the Leevard andcWindward
group of islands is situated in Long t1 45'W and Lat. 12 -N


As/7





r6kEr4At> A1,


-6-


to mix the lime for building purposes. The 'Pierre Taille' (fire-
stone) has already been alluded to.

Lime is obtained from the recent bea..:: coral, and from
an insignificTant exposu-ea of limestone near Sof'zriere.

bulphur has on several occasions been -. rked at the
Soufriers, and at the present time there can be seon the machinery
installed by the American Company wh. unprofitably tried to work
the deposit,

Pottery :- made in small qu..ntities at the neighbourhood
of Choiseul.
One or t.-o river concentrates were examined to see if
traces of gold or .:lver could be discovered. The sample from
Fond St, Jacque (Soufrie2e) consisted chiefly of quartz and fels-
pathic material with limonite, chloritised mica and hypersthene.
No silver platinum cr gold could be detected either here or in the
sample from the Riviere D'Oree. The very pronounced golden tint in
this latter river :-; doubtless due to chloritised r:Lca, which was
identified in the analysis in spite of its rarity in microscopic
sections.

St, Lucia a;pears to be or- of the few West Indian
Islands where there is unlimited wat3r supply at all times of the
year and in view of the simple berthing facilities at Castries,
steamers are often wort to come in a id takes or. s-pplies of fresh
water.
Sgt. T('.reeth W. Earl.e M.Sc., F*I.C.
Govcrrment Geologist to the Wi1dward and
Leeward Islands, SepGt 6th. 1923.


1901 JoW, Spencer.


1901-2 J.W. Spence.


1903


1904

1905


K. von S-e :,r


O',o0 Hove.

. .T Hill


In Press T, Vaugh1_.:i.
and Prof. r...vey




B GEOL B .
[A^> (By .:.


The Geological and Physical Development
of Dominica, with Notes on St. Lucia etc
Q.J.G.S., LVII,
The Windwced and Leeward Islands.
Trans. Canadian Institute.
Zur Kentniss der Inseln St. Lucia,
Monserrat, Nevis c-nA St. Kitts.
Centralblai t fur Min. Geol. and Pal.
Soufriere de Sainte Lucia.
B.G.S.A., Vol. 16.
The Evolution of the Windward Archipeligo.
B.G. SA., XVI.
The Igneous Phenomena of the West Indies*


ICAL SURVEY GRErNAOAi
V. Earle, M.4 *. ::' -So- )


A. TOPOGRAPHICAL

Grenada, th6 most southerly of the Leevard andcWindward
group of islands is situated in Long t1 45'W and Lat. 12 -N


As/7






-7-

As is usual in islands of this group, it is characteris-
ed by one exial range of mountains situated excentrically(nearer
to the Leeward than to the Windward Coast) and throwing off lateral
branches to the sea. The highest points of the ran-ge are at Mt.
St. Catherine (27'.7 ft) towards the Northern end Jf the island,
and the S.E. Mounta n, (2359 ft) and Mt. Sinai (~j~0 ft) at the
south end of the rat.ge. Owing to the external position of the
main range, the rid es are much steeper and the valleys more ravine-
like on the Leeward side of the island than on the Windward where
the land slopes ge t'ly to the sea, of e:r. with extensive coastal flats
on the sea margin. The southwestern end of the island is prolonged
into promontory or. which is situated the Point Saline Lighthouse.
The northern half of the island on both coasts presents a fairly
straight coast line, but at the souti end this gives place to an
excessively indented coastline, consisting of a succession of narrow
embayments up to two miles in length running up into the land.

The Capital, St. George's, is situated on a deep harbour
which w. ud, if it were properly dredged, allow steamers of average(
size to berth alongside the wharf. -'he southern part of the harbour
known as the "Lagoon" is separated f-'om the main harbour by a coral
reef on which the original settlement stood. The town is prettily
situated on the neck of land separating this harbour from the main
Leeward Coas't The only other safe harbour is at Grenville on the
Windward coast which is :-3ndered dangerous to entry at night or to
large boats by the extensive coral reefs impinging: on the shore.
Sloops can also anchor w.th tolerable safety except in rough weather
at Sauteurs, at the extreme north end of the island. The island
is well watered wit. streams, many of which flow all the year round.
There is no deficic-. y in the water supply, even in the driest months
of the year.

The main :-oad vhich completely circles the island is -
considering the tc:-:oraphical conditions an excellent one, in
addition to this thee a-e two roads which can be Itraversed by car
across the island from east to west one from Grenville to Gouvave,
the other from Gren- ille to St. George's. At the highest point on
the latter road is ,situated a lake is known as the Grand Etang:
this forms the sour-.( of the Great River, the largest river in the
island.

The lake probably indicates the site of a previous crater,
as does also the perfectly symmetric.il cone-shaped depression
containing Lake Antoine in St. Patri-k's parish, Another crater
may be represented by the "Punchbow3l (which contains no lake) on
Mt. Rich Estate, but all these have been long extinct, as there is
no record of volcanic activity in Grmnada in historic times.

In addition to St. George's there are four small towns
situated round the ccast, Gouvave and Victoria on the Leeward Coast,
Sauteurs on the Northern and Grenville on the Win'dward coast.
Communication down the Leeward Coast is maintained by road or motor
boat service and on the l:indward by a Government Motor Mail service.
The staple crops of the island are co-oa, nutmegs and spices.
Sugar is a subsidiary product.

B. GEOLOGICAL
While Gre-rada has, generally speaking, the geological
aspect of some of .,h other islands, kg. St. Lucia, yet it has
characteristic feat: -es all of its owil Composed in the main of
massive laves and pr'ocl&stic rocks it yet has a considerable
development of fos.-, .iferous stratified sedimenta-;ry beds which while
not presenting the detailed geological succession of the Antigua
deposits should, on determination of the fossil remains, throw


considerable/8






-8 -


considerable light on the geological history of the district.

The mountainous parts of the island are composed of the
later pyroclastic rocks and disintegrated lava which have been
broken down by chemical decomposition into a soft a:olinised 'tiff,'
The lower lands are gene-rally constituted by tuffs a-d conglomerates,
except in some of -s headlands where lava flows ari seen to reach
the sea. Often ther3 is a large amount of massive xundecomposed lav
scattered about over the land and in some parts of the island, e.g.
Black Bay and Woodfo-d these boulder formations are so pronounced
as to make any form of cultivation an e--tremely difficult matter.

The tuffc apart from there tsual form of loose incoherent
friable deposits, full of boulders of massive rocls etc., frequent-
ly show a very marked appearance of bedding. A very striking instance
of this is seen at Ballast Cliff at %the mouth of St. George's Har-
bour on the south side. From the sea this cliff appears to show a
slightly foxlded series of grey argillaceous and calcareous rocks
such as might be presented by a section in the Upper Lias of England.
A closer inspection shows that the d-posit consists of nothing but
rolled fragments of volcanic ash, scoriae etc., practically without
cement and containing only a few larger sub-rounded lumps of andesite.
The grading of the deposits into coarse and fine layers has given
the deposit the appearance of bedding, and the false bedding is
accentuated. into apparent unconformity by the various angles on the
face of the Larry. The beds are undoubtedly tilted and in the
roadside quarry dip 200 t- 250.

A similar section is seen in the sea cliIf at Queen's
Park. Here the ear -er deposits, folded into a syncline, are over-
lain in marked unco; ':riity by further pseudo-stratified beds, fold-
ed into an anticlir most of the Material is well rounded but a
few larger sub-arnli;-r boulders occur. The bedded appearance is
still further accent -ated by differential weathering.

Another tion in the same deposit on the north side
of the park shows a mass of red ferruginous scoriae and cinders
exhibiting fine fals' bedding, the "stratification" being marked
by varying degrees o coarseness of material and bands of larger
and smaller rock material in the mass. There is a complete absence
of cement, and the .:posit is composed entirely of rsll rounded
fragments varying i_ size from that of a pea to that of a walnut.

The complete absence of cement in such Leposits shows that
they can nsit'er have been consolidated under the sea or as torren-
tial deposits; they must, in fact, represent subaerial deposits
formed by successive showers of well rounded lapilli and scoriae,
which have been sorted by gravity, a&d the apparent unconformities
in the deposit represent denudation Curing pauses in the volcanic
activity

A fine section of the more normal tuffs is seen where
the main -cad crosses the river Antoine at Tivoli; here, during
pauses in tie volcanic activity, small streams hIrve eroded their
way through ~he ash beds and during later eruptions have been
gradually filled up by su sequent showers of coarse ash and sand.
That these ash and tuff bods were not always the list products of
volcanic activity is show by such sections as that near the St.
John's River, mil.s fr-m St. Georges on the Graind EtangsRoad.
Here the roadside se tion shows fine grained tuffs with some large
boulders overlain b, black basalt. The basalt cute across the bed-
ding of the tuffs *-.'. for a depth of eighteen inches has baked them
into a com-pat reddish coloured depoa'- showing srnall scale coc!mnar
jointing. Ine river has subsequently cut its way through tuff and
lava together


Tuffs/9





- 9 -


Tuffs and agglomerates are seen at many other places
round the island. At River Antoine the beds are sufficiently
cemented to afford a rough building material for estate works,
aqueducts, etc.

In addition to these small tuffs and agtlomerates, which
are largely subaerial in origin, thee are in Grenf-da other very
important ashes whi..1 are extremely v.ell stratified and have all
the appearance of bing water deposited. These are yellow to brown
in sppecarnc.- and : often so fine grained as to merit the name
of clay or silts* 1-iey are often very hard and break with a con-
choidal fracture, wlIle at other times they can be split into thin
laminae like slate. Such clays have been recognized at many points
in the island, par' .:ulally by the waterfall on the road to Annan-
dale, above Tufton Hall, and in the sea cliffs between Sauteurs
and Levera.

At the former locality the rccks were fcurnd to contain
matted needle like c.?ystals of Gypsum, while above r''ufton Hall, in
addition to thin pt tings of carbonaceous material, there is a thin
bed, one inch wide, of crystalline gypsum interbedded with the
shales.

While at Levera these beds occur at sea level, at Tufton
Hall they occur spasmodically from 300 to 400 ft, (being exposed in
the river bed just by the Tufton Hal "Gap") to 900 or 1000ft. They
appear to be mixed up i. heterogeneo ,s confusion with the compact
ashes ar.d pyroclastic rocks, by whic1 they can be seen at different
points to be both over and underlain.

Repeated search has been made in these strata for fossils,
but with only moderate E.v.cess; at Annadale and Levera badly
preserved pl -at remains may be found but no marine or other inverte-
brates. Specimens of the.e plants and of others from Golden Grove,
Calivrigny, were submitted to Prof. Gordon of King's College, London,
and he informs me that th3 plants are all of recent species but
that the material iE not sufficiently well preserved to assign specific
specific names to thm.

At one pir.t towards the hill known as "Daniel" (Tufton
Hall) fine beds of' .ack friable shale interspersed with beds of
harder yellow clay with conchoidal fracture are seer to dip 45 -
70 S.W. to 8.S.W. &iwn the valley towards Mt. St. Laurient they
are seen to be dipping equally steeply N or NNW and close by one un-
scaleable waterfall rhe arch of the anticline can be seen. Still
lower down the street i a small fault is witnessed by adjacent beds
dipping steeply in opposite directions.

At Levera 'he dominant dip is South, but at several points
the beds are folded into a succession of very sharp anticlines, the
axis of folding being approximately east and west. On sandy islands
there are yellow marls und shaly bed. dipping 60 SS8E These are
overlain by perched boulders of Oliv:ne Basalt which form the highest
ground of the island. Similar beds cccur on the mainland in Grenada
Bay.

In every caFe the axis of folding appears to be approxi-
mately E. and W. and it is interesting to note that this is the
direction of folding in Trinidad, so that it is possible that Grenada
underwent to some extent the same earth movements (? of Miocene Age)
as Trinidad and ? Barbados.

In the neighbournood of Westerhall and Calivigny there
is a development of somewhat similar bedded rocks; they are usually
more ashy and gritty than those of Tu-'ton Hall, Levera and apart
from small local dis rubances, are practically horizontal*Exposures


near/10





- 10 -


near Golden Grove yielded plant remains and leaf impressions.

Horizontal. stratified beds occur at an altitude of over
700 ft, below the lunatic asylum ( St. George' s). 2hese are for the
most part of a more gritty and ashy nature and di. not yield any
plant remains or othar fossils.

Thise various beds are alr..st certainly of lagoon or fresh
water origin and it is probable that they were formed under
terrestrJal conditions in a manner comparable with similar deposits
of Skye -d Antrim. In the latter 1ccalities between successive
sheets nZ lava are four a continuous group of clays, lithomarges,
pisolitic ironstone, tuffs with good plant remains (which have fixed
the age of the lavas) a-:d even workable beds of lignite and coal up
to a foot :n thicknesse

TLht there is nothing inherently irpos3ibly in the finding
in Grenada o Marine beds at an altitude of 700 At or more is shown
by the discovery of Mariyi Limestone at Columbier at an altitude
of over 600 ft, This limestone cont:.ins corals e.., ?Macandra
strigosa (Dana) and otherr marine fossils, such as mu.nute gasteropods
and foramini.era whL h are all probably sufficient to determine the
age of the deposit.

Numerous .her deposits of limestone occur in the island
and among them may mentioned the exposures at Mount Alexander
(Sauteurs) a4 varic points on the Dougaldston and Pulmiste Estates
(Gouyave)y at the Te.-pe (two miles from Sto George's., These lime-
stones are generally in patches of small extent, ribedded and contain
abundant fossils, su h as foraminifera, gastropods (Bulla, Oliva,
Solarium, Conus, Oe: .+hfur etc.), Lamellibranch (eactan, Otrea,
Lucina etc.), ?Algp ., urbinate and conipound corals e.g. ?Orbicella
annularis, Ellis a_. Sol. and Echinoid remains. T'ese latter
exposures (as disti nt from that at Columbier) which are never very
high above sea level are probably of Pleistocene age.

The volcanic rocks of Grer da are grouped by Harrison
under five headings:-

i Hornblende andesite
2 Hornblende Augite Ande.ite
1 Augite Enstatite Andesite
Augite An-lsite with Olivine
Olivine Bsalt

(I:- a footnote Earle adds that the "Enstatite" of 3 is
r-re probably 'ypersthene)

He gives detailed descriptions with loc&aaties for each
type but observes th .t "the lavas of the island show little or no
signs of regular dia ribucion".

These t -. being all fairly well defined and common in
other WeEs Irdian I, ands it will suffice if we call attention tW
one or two rather P optionall examples of the various types.

Amongst the Olirine Basalts may be notice the lava flow
previously mentioned as baking the tuffs in St. Jch,'o River near
Tempe Estate,

This is a ine grained rock, tke only mineral occurring
in large phenocrys. being Olivine, wh::ch shows extensive invasion
and alteration by liri-nitic material. Augite is Tnesent in small
prismatic crystals but felspar is war tingo The groundmass is
microcrystalline consisting of Olivir,, Augite ain ?Plagioclase.
The rock thus approximates to a Limb-rgite.


A very/11





- 11 -


A very common rock and one almost peculiar to Granada
nri Carriacou is an Augite Basalt or Andesite of which the Great
Anse rock is a good example. Under the microscope the rock consists
of very large phenocrysts of Augite, which usually show "Zoning"
and "Hour-gPi'ss" :structure, associated with large crystals of
labradorite felspar' with accessory iron ore and olivine in the
ground mass. In the hand specimen the augites are large and black
and often come out of the rock whole when they aie seen to consist
of perfectly crystallised eight-sided prisms terminated by clino-
domes. From Madey'k Estate a tinful of these weathered-out crystals
was collected from the surface of the ground in a short space of
time.

The other two striking rock, are those from the Grand
Etang and Callvigiy Island. The former consists of large brown
hornblende cryst?_s comprising 2/3rds, of the rock, associated with
and enclosing rci:rd colourless crystals of augite, the whole set
in a background of large felspar crystals. Biotite, usually a rare
mineral in West Indian Lavas, is an important constituent. The
Calivigny rock consists of dark brown hornblende, and pale green
augite and Bytownite-Anorthite Felspar in about equal proportions.
The Calivigny rock is comparable with the Anorthite Olivine rocks
of St. Vincent, Both rocks are entirely holocrystalline and approxi-
mate to gabbros. At Calivigny Islani, large lumps of massive Horn-
blende and Augi~e without felspathic cement can be picked up.

At the Quarantine Station for the top 6' of the cliff and
overlying yellowish white tuffs ther- is a markedly red rock, which
on close inspection proves to be a ferruginous red breccia of
volcanic rock.Unde." the microscope ths rock is an augite basalt,
consisting of small crystals of aguite and felspar with a ferrugious
cement.

No dacites were recognized amongst my Grenada slides.

Speaking generally the rocks of Grenada are noticeable in
contrast with those of the Leeward Islands for their greater basicity
for the almost universal occurrence of Olivine and f'r the develop-
ment of Hornblende end Augite at the expense of Hypersthene, though
the latter mineral is occasionally present. That is to say there
is a predominance of Olivine Basalts over Hypersthene Andesites.

The characteristic features of the rocks of the whole
group of islands are the rarity of mica in any form end the almost
complete absence of the fslspathoid group of minerals. With a few
notable excep.ion.s. e.g. the rock from Petit Piton (St. Lucia)
Quartz is not a common mineral. Such isolated lumps of plutonic rock
as have been founi must have been torn off in recent eruptions from
some deep seated magma.

Many mineral springs occur in Grenada. Most important is
that at Chambord, where the carbonated water has given rise to
extensive surface deposits of Travertine. The water from this
spring and from the hot spring at Peggy's Whim were analysed by
Prof. Harrison who suggested the usefulness of the former in treating
chronic l-'ver complaint- produced by long residence in hot climates.

There is a small soufriere high up on the slopes of Mount
St. Catherine at HFpsac,,

C.ECONOMIC

Although it is not anticipated that any commercial
development of minerals w:.ll be possible in Grenada, there are never-
theless a few occurrences that must be put on record.

With regard to the prospect of oil being found in Grenada


I have/12





- 12 -


I have little to add to the rep .t-of Mr. TeE, Penny to the
Government of Grenada in 1920.

As Mr. Penny pointed out, the phenomena considered
indicative of Petroleum In Grenada consist of mineral springs, coal-
mistaken for manjack and pitch. The first are no indication what-
ever of petroleum, the coal consists of anthracite scattered about
on the surface of the land on the Leeward Coast, and was evidently
at one time imported for use in the f.ugcar mills, etco, and the pitch
is jetsam on the beach, i.e. of seaborne origin.

Two 01 three of the local residents took me to places on
the beach where the pitch "had been seen actually oozing out of the
cliff" but on no occasion were they able to show me the phenomenon,
or indeed any trace of the pitch except splashes on the beach
boulders,

Bedded with the clays at Tufton Hall there was found a
small slab a fev inches square and i inch thick of a black, brittle
asphaltic substance mixed with shale. For a complete investigation
of this material samples of at least 7 lbs would be required, but
there is nothing in the substance incompatible with terresti&l origin
such as we have postulated for the formation of these shale beds,
and nothing in it necessarily indicating the occurrence of petroleum
in the strata.

It is utterly fallacious tj point out the proximity of
Barbados and Trinilad as an argument in favour of the occurrence
of oil in Grenada, when it is pointed out that there is no resemblance
geologically between the islands; ii is not unlikely however, that
the Grenada pitch may have drifted from Barbados or Trinidad* From
what I saw of the g- & and surface "indications" I can see no
prospects of oil being found in Grenada in paying quantities.

There ib a curious occurrence of copper ore at Sauteurs,
that has cuased tle writer some perplexity*

This consists of heavy lumps of metallic material scattered
about on the cliff pasture just east of the mouth of St. Patrick's
river.

An analysis of this material made in America in 1915 gave
the following result:-

Copper ............................72.20
Lead1................................17, 62
Tin.................................... 8.10
Zinc.. ..................... ......... 1 15
Iron... ..........................*.. .22
99. 09%
The Liaterial was not considered to be an ore but some
kind of Lurnace 1 ?oduct.

A further analysis was mad, by the Imperial Institute,
London, 1922 as follows:-

Copper.. .. .... ........... ......o. ..65- 4
Lead..**... o .... .*************l334
Tin................................. 9,48
Zinc ...,,......*..............**..... 0, .C
Silica." ..... ........... .......... 0.7
Ferric Oxide....................... 0.41
Alumina..******...................... 105
Lime****lfl***********.cc.ccc....... 0.21
Le.gnesia. ** **** ... ................ 0o21
91.04%
Gold/13








Gold.. ******o oo o i *oo.***ees, 2 dwt per ton
Silver..o......................o..0.24.8 2oz per ton.

"The substance has the appearance of a slag and contained
pieces of coke. Its composition and appearance indicates that it
probably insists of the weathered remains of an alloy of copper
reworking or smelting."

The latter suggestion is confirmed by tie finding on the
spot of the foundations of a ruined Juilding and one would be
inclined to ignore the substance at once as of artificial origin
were it not for its peculiar composition (the high proportion of
silver and lead alone suggesting thal it cannot have been a foundry
alloy for the production of anything like a still) and for one or
two sus-icious indications in the field.

On the cliff immediately below the pastures where the
copper is found thera is massive grey Andesitic Rock full of loose
volcanic e&ectamenr a and vividly stained with copper carbonate
(Malachite); this fissure could not be traced inlad or any further
evidence of malachite found, except in a small surface exposure
some 4 mile away close to the Levera Road. At the crest of the hill
near here and adjoining Lr. Buxo's hcuse there were 0,t one time
three holes, the largest of them 3' in diameter and 40' deep, which
were filled in by the present owner of the land. The object of
these is not known, but from their situation at the crest of the hill
it is unlikely that ;hey were intended for wells. Close by here
the present writer found two or three lumps (about 1 lb in weight)
of Black Hematite3

Finally, from the slopes of Piton on Madeyo Estate several
large lumps of massive. mclachite have been found. Whether these
various indications point to previous attempts to minor and smelt
copper on the spot cannot be said without further investigation,
such as drilling. The rocks are not such as are likely to carry
important copper ores, nor is it probable that the ore could have
been smelted on the spot so that the writer is inclined to believe
the substance to be of artificial origin, unless i'urther evidence
can be found of copper ores in the neighbourhoodA

A curious variety of haemeiite or specular iron ore
occurs at the head of Concord Valley and elsewhere in the islands.
This consists of tabular hexagonal o:' twinned crystals of rather
unusual form. The crystals are of a brilliant steely lustre and
are always found qaite fresh in the decomposed Andesitic'Tiff'.
They consist of 97 9895% Iron oxide, but are o!Lly found in
quantities to be cf mineralogical interest.

Black beach sands occur in several localities round the
coast of Grenada. These :onsist of Augite, Olivine, felspar,
magnetite and ilmenite an*, are comparable with similar deposits
described from St. Kitts. Professor Harrison who had as essay made
of the sand from Black Bar, found it to contain 14 grains of silver
and 4 grains of gold to the ton.

A fair sized lump of well crystallised Muscovite mica
was presented to me from Sauteurs. This is of interest in view of
the fact, commented on above, that mica seems to be a rare mineral
in all volcanic rocks from these islands

II THE (GRENADA) aRENADIgES

The urenadiin Islands attached to G-e.ac.a comprise the
islands of Carriacou, Petit Martinique I. de Ronde, I. de Caille,
Kick-em-Jenny and a number of smaller unimportant cays.


Carriacou/14






- 14-


Carrlaoou itself is the largest of the Grenadine Islands,
having a length of about seven miles and a maximnr. breadth of 21
miles. It has an axial range of hills rising in height to 960'
at Chapeau Carre at the south end of the island, 830 behind Hills-
borough and 980' at North High Hill, The town of Hillsborough is
situated on the Leeward side of the island, and many small harbours
exist on the Windward side, protected by fringed coral reefs. There
are no rivers on the island and all the water used is caught off
the roofs and storel in tanks, so that there is frequently a short-
age in times of drought. Broad and well graded roads extend all
over the island; were there the traffic to warrant their upkeep,
there would be in Carriacou a better and more elaborate road system
than in any other of the small West Indian Islands.

The island is extremely fertile and is largely in the
hands of peasant proprietors, the one thing mitigating against
economic prosperity being the inaccessibility of the island, the
only means of access being by sloop from Grenada, a journey employ-
ing anythingg from eight to twenty hours.

Carriacou is important r:oologically on account of the
widespread development of fossiliferous marine limestone. The whole
of the western half of the island, i.e. west of a line drawn along
the central rangE to the Windward cast at Dumfries is made up of
volcanic agglomerate, lavas and tuffs. Decomposed andesitic lava
is seen in situ at various points but no large occurrences are
exposed. A commoner type of deposit appears to be a ginger-bread
colour tuff, such as that forming the Chapeau Carre* By the roag-
side just near the northern extremity of the island these dip 15
NE and contain abundance of beautifully developed and weathered
crystals of au3ite, 1tst like those obtained from Madey's, Grenada.
Residual boulders of the augite basalt from which they were derived,
are seen on the summit of Chapeau Carre and in the volcanic agglom-
erates*

Limestone occupies the surface over most of the area east
of a direct line drawn from Windward village to Dumfries. It is
first met with near the top of the central ridge and it would there-
fore seem to overlie the tuffs and agglomerates forming the western
half of the island. At the summit of the Limlair-Belair Ridge,
however there are ginger bread tuffs and boulders of basalt resting
on the limestone, so that, as we have shown elsewhere, the de-
position of limestones was only episodal in the general volcanic
activity. In this latter the tuffs are characterized by leaf
impressions and remains exactly analogous to those obtained from
Golden Grove and elsewhere in Grenada.

At Dumfries too, limestone is seen overlying volcanic
breccias and agglomerates. This is overlain by decomposed andesite
which again in its turn is covered by chalky cream coloured lime-
stones, the limestones overlying the tuffs containing fragments of
volcanic material derived therefrom.

The limestone appears to be made up entirely from cal-
careous algae,(e.g. Lithothamnion sp?). At Dumfries there are also
huge amorphous oysters, sometimes showing coarse corrugations on
the shell, the onjy other fossils sean being small Pectens and a
species of Liothyrina.

A very interesting section is seen at Kendeace Point. In
the bay there are roughly horizontal beds of rainwash, ash and
surface soil, while at the point going south there are well strati-
fied yellow marly beds ani harder ash and limestone beds, the whole
dipping 27 WNW. Below these round the point are ginger-bread
tuffs with small cugite crystals and chips of augite basalt, dipping

at/15





15 -

at much the same angle as the last and overlain in marked unconform-
ity by marine limestones. In the next bay the limestone beds are
interrupted by two faults for a space of 20' or so, the limestones
and marl being vertical. These are succeeded again by limestone
and marl dipping 15 SW. The lowest accessible beds are highly
algal limestone with boulders of volcanic rock at the base; oysters,
Pectens and other lamellibranchs also occur with fragments of
Scalaria and echinoid spines*

The determination of the age of this deposit is of consider-
able importance in unravelling the geologic history of the West
Indies, and I regret that owing to the absence in England of type
material with which to compare my specimens ( moat of the type
fossils from West Indian localities being housed in American Nuseums).
I have not been able with certainty to fix the age of the deposit.
The limestone however appears to have affinities with the White Lime-
stone of Antigua (of Middle Oligocene Age) rather than with the
Pleistocene deposits of Grenada, though it should be noted that where-
as the Antigua beds dip NE the dominant dip in Carriacou is SW.

JACK-a-DAN a small island about one acre in extent in
the harbour off hillsborough is composed of massive andesite. This
is traversed by thin sheet veins of mineral substance which, on
investigation, was.found to consist largely of pyrolusite (MnO )
with chalcopyrite, malachite, hemn.tite and limonite. It was found
to contain 23.32% of copper but no nickel was detected.

I. de Caille, is a rugged island composed entirely of
black vesicular basalt, in loose red scoriae and cinders. On the
east side of the island the headlands consist of one mass of Jagged
boulders of lavas piled cn top of one another and extremely trying
to walk on.

The rock is a vesicular olivine basalt, with subsidiary
augite, the felspar occurring in lath shaped crystals with black
glass in the groundmass.

On the beach these basalt boulders are often cemented to-
gether by recent coral lime into a conglomerate, and there is much
of the jetsam pitch that has been noted in previous reports.

I. Ronde is composed of jointed basaltic lava and volcanic
agglomerate. There is much more cultivation than on I. de Caille
as the surface of the island is no so rocky.

Kenneth W. Earle, MSc.,FGS.,
October 2nd. 1923 Govt. Geologist, Windward and
Leeward Islands.

BIBLIOGRAPHY
1896 J.B. Harrison The rocks and soils of Grenada and
Carriacou.
London.
1902 J.W. Spencer On the Geological and Physical Develop-
ment of Dominica with notes on Martin-
ique, St. Lucia, St. Vincent and the
Grenadines.
Q.J.G.S, Vol. 58.
1903 Klvon Sapper Ein Besuch der Inseln Grenada.
Centralblatt fur Min. Geole und. Pal.
1902 J.W. Spencer The Wincward ani Leeward Islands.
Trans. Canad. Institute.


The/16










1905


E, T Hill


1921 --------
In press T.oo.Vaughan and
Prof. Hovey


The Evolution of the Windward
Archipelago.
Bull. Geol. Seco America.
Handbook to Grenadr,
The igx-eous phenomena of the West
Indiese


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