The daily morning journal and courier. [volume] (New Haven, Conn.) 1894-1907, 1898-06-07
A WEST INDIAN CONTINENT.

Feet Higher Than Now-Changes of
Level Through the Ages-Mexico and
Central America Recently Raised
West Indian Lakes Once Drained Into
the Pacific.
A glance at a map of the American
continent inclosing the West Indian
seas within it's mass suggests that
these basins are sunken plains, sub
| merged to only moderate extent, but
| the soundings show depths reaching to
more than three miles. "It is not too
much to say that every spot which is
now dry land has been sea at some
former period, and every part of space
now covered by the deepest oceans has
been land" This enunciation still held
| place among the latest writings of the
| great geological teacher, Sir Charles
Lyell.
Such great earth movements are slow
| pulsations, extending over large con-
| tinental 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 usual
! ly these movements do not disturb the
| courses of the drainage of the rivers,
although barriers sometimes do appear
across valleys. The modern changes
of level illustrate these gentle oscilla-
lions. Islands and farms which were
located upon the low coast of New Jer-
sey in the early settlement of the
country are now reduced in size and
are partly converted into salt marshes.
The rate of sinking in this locality has
| NEx MA "a L.,
two feet in a century. The depression
of land about the mouth of the Missis
sippi has lately been measured by e.
L. Corthell, who finds that the sinking
there is at the rate of five feet in a
Gentry. For these low lands this sub
sidence promises to become a serious
economic question in the not distant
future.
On the other hand, certain northern
regions are rising. Thus, in the dis
trict of Niagara Falls, the rise is a foot
and a quarter IN century, or perhaps
a little more. In the St. Lawrence VAL
ley, upon the northwestern tanks of
the Adirondack Mountains, the upward
movement, for the last fifteen hundred
years at least, has been from four to
five feet per century Such gentle
changes, accelerated or retarded, and
continuing sufficiently long, are capa-
Bile of transposing the ocean floors and
mountain heights.
| Numerous soundings, chiefly for the
use of navigators, but occasionally TAX
en- for scientific purposes, have been
made off the American coast and in the
| West Indian 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 extensions of some
of the great rivers have long heen
known. From data thus collected Lin
denkohl traced the Hudson river across
the submerged banks off the New York
and New Jersey coasts to a depth of
nearly three thousand feet. Later, the
writer gathered evidence from the
drowned st. Lawrence, Delaware, Sus-
quehanna and other rivnrs as far as the
Mississippi, and it became apparent
that the whole of the eastern coast of
America in recent times stood three
thou sand feet higher than now, with
suggestions Of a still greater elevation,
which he then hesitated to follow up on
account of their startling character.
The Colorado river, of the West, flows
from table-lands eight thousand feet
to ten thousand feet above the sea. It's
canyon section is about two hundred
and twenty miles long. This is not a
simple gorge, but a broad valley from
five to twelve miles wide, bounded by
walls rising two thousand feet above it's
floor. This floor was an old base level
of erosion formed at no considerable
altitude, so that the streams meanered
sluggishly over it, and the rains and
rills widened it to broad proportions,
but, owing to subsequent elevation of
the region, the river has cut down it's
channel to still lower base level, and
in doing so it has been deepened thirty
five hundred feet or four thousand feet
more, with the production of a narrow
gorge having precipitous walls, not yet
widened into a mature valley. Chan
nels like that of the Colorado also &C.
cur, crossing submarine plateaus.
The low coastal plains of the South
western States do not terminate at the
seashore, but pass beyond, forming
shoals and banks, and eventually sub
marine plateaus, overlooking the edge
of the continent, which is fifteen miles
eastward of Cape Hatteras, but three
hundred 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 one hundred
feet to three hundred feet would great
ly enlarge the Southeastern States, and
raise the Bahama banks into broad
plains lin reality continuation of the
coastal plains of the Southern States),
separated from Cuba and Florida by
only narrow channels. A lower broad
plateau occurs in this same region, at
depths from twenty-five hundred feet
to thirty-five hundred feet. From it's
margin the edge of the continent drops
abruptly to depths of twelve thousand
feet or more. On the western side of
Florida the drowned plains gradually
slope down to about three hundred feet,
beyond which there is an abrupt de-
scent to the abyss of the Gulf of Next
co. The Yucatan plains extand as
broad submerged banks to about three
hundred feet beneath the sea, and the
sea floor then falls rapidly to that of