20 The Daly News. Friday. September 20 199
V.l.'s geologic origins still affect our culture
Last month. I gave a seminar for
a forum on indigenous people of the
Caribbean. My topic was cultural
In my talk, I compared and con-
trasted the ways modern Virgin
Islanders relate to their environment
with the ways of the past. I tried to
explain the modem processes that
make us fell disconnected from the
environment, as well as the ties that
ultimately bind us together.
To understand cultural ecology,
one must know something about the
islands' geology, its flora and
fana, and its human ecology.
Every school child in these
islands should know the geological
makeup of the Virgin Islands,
because life.began here long after
these islands were formed.
The soil types, hills, valleys,
mountains, and other characteristics
of the Virgin Islands are influenced
by the island's geological crust.
Volcanoes, coral reefs, and man-
grove forests have been the builders
of the Virgin Islands ecosystems.
The Virgin Islands forms one
exposed section of a great sub.
merged mountain range that
extends from Cuba, to Hispaniola,
to Puerto Rico to the Lesser
Antilles, ending in Trinidad and off
the coast of Venezuela.
Geologists claim that St.
Thomas's and SL John's origins go
back several million years, to the
late Cretaccous period. This means
that when the Virgin Islands was
forming, the major continents of the
world were probably much closer
The long process of undersea
mountain building and eventual
uplifting of submerged ridges took
the work of explosive volcanoes.
These processes, along with
changes in sea levels, centuries of
coral reef deposits, and further ero-
sion created the Virgin Islands land
formation we see today.
During the Cretaceous period, a
series of volcanic eruptions solidi-
fled on the ocean floor. St. Croix
was never a volcanic island. But
volcanic activities played an indi-
ret role in the development of the
island. The rocks underlying the
mountain ranges on St. Croix are
sedimentary rocks, formed from the
debris of volcanic activity.
The limestone or "white marl"
found at the surface of the Central
Valley is considerably younger than
the volcanic rocks. It is probably
the remains of coral reefs that
formed as the island was uplifted
from the ocean floor.
Other interesting geologic for-
maions include the Virgin Islands
Basin. If you look on a map of the
Caribbean area, St. Croix is separat-
ed from the northern Virgins
Islands by this basin.
The basin between St. Croix and
the rest of the Virgin Islands is over
13,000 feet deep. The Puerto Rican
Trench that is located north of St.
Thomas reaches a depth more than
27.000 fet. This is the deepest area
of the Atlantic Ocean.
At the top end of the scale,
Crown Mountain on St Thomas is
1,500 feet high, followed by Bor-
deaux Mountain of St. John at
1,277 feet. and Mt. Eagle of St.
Croix at 1,165 feet.
'Although St. Croix is not a vol-
canic island, the island is still grow.
ing by coral reefs pushing out of the
ocean floor. This can be seen at
Annually Bay and Well Bay on the
north side of the island.
The geological makeup of the
Virgin Islands also affects the
island's vegetation. In 1923, F.
Borgesen described the vegetation:
"In the wooded parts of St. Croix.
especially to the North of Blue
Mountain, the trumpet wood tree
(Cecropia peltata) is one of the
principal constituents of the woods.
whereas it is rare in the other
He pointed out that such small
species as the "Thrinax," which is
found on SL. Thomas and St. John.
is lacking on St. Croix This differ-
ence is true for a number of other
plants species. The flora of St.
Thomas and St. John is much more
varied than that of St Croix. which
has a more isolated location.
This variation has to do with the
higher elevations in the two small
islands. Crown Mountain on St.
Thomas being some four hundred
feet higher than Mount Eagle. the
highest point on St. Croix. The tcm-
perature in the higher elevation of
St. John and St. Thomas is conse-
quently lower than the temperature
of the higher altitudes of St.Croix.
Higher rainfall of the two smaller
islands enables certain species of
plant to thrive on St. Thomas and
St. John, but not St. Croix.
These differences in the islands,
caused by their geological forms-
tions, also creates differences in the
needs of the people on each island.
Now you know what we mean by
Olasee Davis, who holds a mas-
ter's degree in range management
and forestry ecology, is a St Croix
ecologist, activist and writer.