The morning news. [volume] (Savannah, Ga.) 1887-1900, 1898-08-28
WEST INDIAN SEAS ONCE LAND.
Where Waves Now Roll Vast Plat
eaus Extended.
From the - Ynrk Ionrnal

hnent inclosing the West Indian seas
within its mass suggests that these basins
are sunken plains, submerged to only a
moderate extent but the soundlngs show
depths reaching to more than three miles.
Sir Charles Lyen asserted that it is not
too much to say that every spot which is
now dry land has been sea at some for
mer period, and every part Of space now
covered by the deepest oceans has been
land.
Such great earth movements are slow
pulsations, extending over large CONT
mental areas, but they do not belong to
the phenomena of thrusts which give rise
to mountain structures, nor are they the
effects of volcanic forces. The land rises
or sinks so gently that usually these
movements do not disturb the courses of
the drainage of the rivers, although bar
riers sometimes DO appear across valleys.
Inc modern changes of level Illustrate
these gentle oscillations. Islands and
farms which were located upon the low
coast OF New Jersey in the early settle
ment of the country are now reduced IN
size, and are partly converted into salt
marshes. The rate Of sinking in this To-
caiity has been estimated by Mr.. Mitchell
at only two feet in a century. The de-
preston Of land about the mouth of the
Mississippi has lately been measured by
r. l.. Corthell who finds that the sink
ing there is at the rate Of five feet in
century. For these low lands this subs-
dence promises to become a serious eco
nomic question in the not distant future.
On the other hand, certain northern re-
gions are rising. Thus in the district of
Niagara Falls, the rise is a foot and a
ana fz In, .f,f tsrx aVl,a r.u
more In the st. Lawrence valley, upon
the northwestern TANKS of the Adiron-
dack mountains, the upward movement
for the last 1900 years at least has been
from four to five feet per century. Such
gentle changes, accelerated or retarded
and continuing sufficiently long, are ca
pable of transposing the ocean floors and
mountain nights.
Numerous soundings, chiefly for the use
of navigators, but occasionally taken for
scientific purposes, have been made off
the American coast and in the West In
dian seas. In order to insure mariners
against the occurrence of sunken rocks,
the surveys have often been carried from
the coast all the way to oceanic depths.
Upon the submarine coastal plains the ex-
tensions of some of the great rivers have
long been known From data thus collect
ed Lindenkahl traced the Hudson river
across the submerged banks of the New
York and New Jersey coasts to a depth of
nearly 5000 feet. Later. the writer gath
cred evidence from the drowned st. Law
renee. Delaware, Susquehanna and other
rivers as far as the Mississippi, and it be-
came apparent that the whole of the
eastern coast of America in recent times
stood 5000 feet higher than now, with sug-
gestions of a still greater elevation.
The Colorado river of the West flows
from table lands 5000 to 10000 feet above
fc
miles long. There is not a single gorge.
but broad valley from five to twelve
miles wide, bounded by walls rising 1000
feet above its floor. This floor was an old
base level of erosion formed at no consld-
cradle altitude, so that the streams mean
dered sluggishly over It, and the rains and
rills widened 1t to broad proportions. but,
owing to subsequent elevation of the re-
gion, the river has cut down its channel
to still lower base level, and in doing so
IL has been deepened $500 feet or 1900
feet more, with the production of a mar
row gorge having preclpitous walls. not
yet widened into mature valley Chan
nels like that of the Colorado also occur.
crossing submarine pateaus
me low coastal plains of the South
eastern states do not terminate at the
seashore, but pass beyond, forming shoals
and banks, and eventually submarine
plateaus, overlooking the edge of the con-
tihShtf WlliSll Is llNSen miles eastward OF
Cape Hatteras, but 300 miles distant from
the coast of Florida. They extend to and
include the Bahamas and other islands
These submarine plateaus have various
depths. An elevation of 100 feet TO 200
feet would greatly enlarge the Southeast
ern states and raise the Bahama banks
into broad plains lin reality a continue
ton of the coastal plains of the Southern
states), separated from Cuba ana Florida
by only narrow channels. A lower broad
plateau occurs in this same region al
depths from $500 feet to $500 feet. From
ITS margin the edge of the continent drops
abruptly to depths of 1900 feet or more.
On the western side of Florida the
drowned plains gradually slope down TO
about 300 feet, beyond which there is an
abrupt descent to the abyss of the C1lf
OF Mexico. The Yucatan plains extend as
broad submerged banks to about 800 feet
beneath the sea, and the sea floor then
falls rapidly to that of the Gulf of Mexi-
CO. at IL 600 feet. Such slightly submere-
ed plains of great breadth occur on the
banks between Honduras and Jamaica
The Windward Islands are fragments of
plateau, which an eminence of less than
5000 feet would unite into one body of
land. Both to the east and west of jam
atca there are plateaus depressed to be-
tween 5000 and 1000 feet. Still lower
plateaus are indicated in the Caribbean
sea,Nwhich reaches a depth of 1900 feet
From the existence of these submerged
plateaus 1t becomes apparent that a
change of elevation from 1900 feet to 900
feet would not merely unite Cuba and
Florida but would greatly enlarge the
West Indian lands and almost connect
North America and South America Such
change of elevation would nearly barri-
cade the Antillean water into three basins
the Caribbean sea. the Sea of Honduras
and the Gulf of Mexico. The Sea of Hon
duras, between Cuba and Jamaica, reaches
the phenomenal depth of channel of 20 1000
feet, in the form of a long, narrow chan
mel.
Applied 20 the West Indian region and
adjacent parts of the continent, IL would
thus appear that these regions stood from
10000 to 1900 feet. and in some localities
l4,000 feet higher than now. The West In
dian bridge reached hight of from two
to more than two and half miles, while
the floors of the Gulf of Mexico, and the
Caribbean sea, TO which depth the drowned
valleys can be traced, were continental
I zn0tvs