Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-10-15
D. c. UNDER SEA SIX
TIMES, IS THEORY
GeoIogist Reports on Various
SubmerSionS of District in
Million Years.

Six times in q million years much OF
the District of Columbia has been at
the bottom of the Atlantic Ocean.
Such is the conclusion reported to
the Washington Academy of Sciences
by G. Wythe Cook Of the United States
Geological Survey, who studied the geo.
logical history Of this locality from the
start Of the pleistocene era, the age of
the great glaciers, which Immediately
preceded the present. Each emergence
Of the site of Washington from the
ocean left its characteristic traces.
At the end of the pliocene era, just
before the giaciations this territory
stood high above sea level. Chesapeake
Bay was broad valley. The Potomac,
Cook reports, took drop of about go
feet at Little Falls down to the coastal
plain and continued to the sea through
broad valley between gravel-capped
uplands. 1t was deep, rapid river.
Tides Extended to Harpers Ferry.
Then came the pleistocene era. with
the sea 265 feet above its present level.
merged except gravel-covered island
which rose 40 feet above the water
southwest of washington. There is
fiat-topped ridge just southeast of
Bailey's Crossroads, Va, which is
remnant Of this ancient island, known
as the Brandywine Terrace. Tides then
extended up the Potomac almost to
Harpers Ferry.
This all changed radically when the
first of the great glaciations, the
Nebraskans, spread out of the north
over the continent. The tidal waters
receded. The Potomac flowed again in
approximately its old channel. Then
the NebraSkan ice melted, releasing q
vast amount of water to the sea, which
arose about 215 feet above its present
level. The river emptied at Georgetown
into bay about seven miles wide, with
q prolongation extending eastward to
Laurel At this time was formed the
Coharie terrace along the Atlantic
Coast. Mount Pleasant and Meridian
Hill Park, Cook says, are remnants of 1t.
Again came the ice, the Kansan
glacial stage, and waters receded before
It. They came back again when the
ice melted, but only to 160 feet above
present sea level. All Of washington
below Florida avenue was again under
water and the Sunderland terrace was
formed, which follows the present BLUM
Just north Of Florida avenue between
Connecticut avenue and Eleventh street.
Tides in the river reached above Great
Falls.
Downtown District Submerged.
Another glacier came, the Illinoian,
0epleting the seas and draining the
tidal waters of the land. When the
ice melted again tides returned, but
only to about 95 feet above the present
sea level. They extended up the Po-
tomac only to the foot Of Great Falls.
Downtown washington was again under
water, but parts jutted out, forming the
Wicomico terrace. This now is repre-
scented by Capitol Hill and by the To-
calities Of Dupont, Scott, Thomas and1
iowa Circles.
The Iowan glacial stage succeeded,
again the ice melted and again the
seas returned, but this time only to an
altitude of SIS feet above the present
level Tides extended up the Eastern
Branch to Berwyn. Capite Hill was an
island in Potomac Bay. IS biologists
call the arm Of the oce. n which ex-
tended up the Potomac @ailey, Other
parts Of the city formed the Chowar
terrace. of which r and " streets, La
fayette Square and Union Station Plaza
are the present remnants.
The next stage was the Wisconsin
glaciation era, the last Of the great ice
invasions. But at some period in its
progress 1t was interrupted, q great
deal Of the ice melted and the sea level
was raised about IS feet above the
present level. pennsylvania avenue be-
tween Peace Monument end Fifteenth
street was flooded and most Of South
west washington was under water ex-
cept an island at the present site Of the
Department Of Agriculture buildings.
Again the ice returned and lowered the
sea level, but at the beginning Of the
recent epoch the water returned to its
present stage, with tides in the Potomac
and Eastern Branch stopped ut Little
kals and Bladensburg, respectively.
shore Line Changes Universal.
There Is accommodating evidence that
me same changes in shore line hold
throughout the world, Cook saws, be-
cause every coast would be approxi-
mately equally affected by an increase
IN the amount Of water in the sea.
What made the yea rise and fall ut
last six ttmeS?" lb< asks in his report
% the WaShingtor Academy. Glacial
control Of sea level appears to be the
most effective cause. When the great
Ice caps accumulated on the land DUR
ing each glacial stage there was less
water IN the sea than when the ice caps
were melted and the water was restored
20 the sea during each interglacial
stage. 1t has been estimated that If
the ice caps on Greenland and on
Antarctica were melted the sea would
% raised 200 feet above its present