Evening star., 1951-12-12
Great Cliff Found in Sea
Off the Florida Coast
Biologists Report Discoveries
In rs, 1000 -Squore-MiIe Survey
By Thomas R. Henry


An enormous undersea cliff from
5000 to 5000 feet high and extending
for an undetermined distance has been
found underneath the Gulf of Mexico
off the Florida coast.
This striking and hitherto unknown
feature of sea-bottom geography is re-
ported in bulletin of the American
Association of Petroleum Biologists by
G.. F. Jordan of the Coast and Geodetic
Survey.
1t has been believed in the past that
the Gulf floor was relatively level plain.
This is far from the truth, the Survey
party found in exploring more than
$4,000 square miles of which there has
been no previous knowledge. The survey,
carried out by means of the fathom-
eter which. attached to ship, gives
a continuous picture of bottom contours,
was especially of the continental shelf
off the slope of the Apalachicola River.
The sea bottom slopes off gradually
from the land, the fathometer records
showed until depth of about 5000
feet is reached. Then comes the sud-
den drop which probably averages 1000
feet in few miles. In places the great
cliff is quite steep, but on the average
its slope is estimated at about a 35-
degree angle.
Due to "Fault Escarpment."
While the Coast and Geodetic Survey
men themselves make no effort to in
terpret the phenomenon it has been ex-
planned by biologists as probably due to
fault escarpment," definite break
in the crust of the earth which they
believe can be found eventually along
most continental slopes. They often are
be leveled out near the land by the
constant process of erosion.
Underwater pictures of the cliff show
that in places it is very steep, much
more than the postulated 35 degrees.
The survey party was elaborately
equipped to get an accurate picture of
the sea bottom. Tied up with the fa-
thometer, or automatic electronic depth
recorder. was another instrument de-
veloped in the Surveys laboratories
the electronic position indicator. This
gives surveying ships position accu-
rately to within rs yards in 375 miles.
On the continental slope itself before
reaching the escarpment, the Gulf floor
was found to contain many small hills
or domes, from 20 to 25 miles apart They
reached heights of about 25 to 80 feet
and some of them were as much as $500
feet broad at the base. At first there
was speculation that these might be the
same as the so-called salt domes" found
off the coasts of Texas and Louisiana
and which are considered indications of
undersea oil deposits.
1t is pointed out in the report, however,
that the structure of the Florida coast
does not favor such features and it is
probable that these little hills are reefs
built up from the sea floor through mil
lenniunls. They are considerably smaller
than their counterparts farther west.
Hills Are Symmetrical.
The fathometer showed, Mr.. Jordan
said, that the hills are extraordinarily
symmetrical, as if they had been built
according to geometrical plans, which
hardly would be the case unless all were
due to common cause, such as being
pushed upward by some force far under
the sea floor.
Another remarkable feature was the
so-called DeSoto canyon, a great valley
approximately 600 feet deep running
through the continental slope under
water from 1000 to 5000 feet deep. Much
the same feature has been noted farther
west and has been interpreted as desig-
mating an old mouth of the Mississippi.
There, however, it has largely been
filled with sediments from the land and
its existence is determined only by
sounding apparatus.
On the Gulf floor beyond the great
ridge are several larger hills than those
on the continental slope for which no
explanation has been offered.
The unexpected findings are inter-
preted by Paul Weaver, chief geophysi-
cist of the Gulf Oil Corp, as indicating
that the Florida peninsula is most likely
part of the Caribbean area of the
earth rather than of the lands to the
west 1t also indicates, according to
another Interpretation, that the floor Of
the Gulf has foundered, probably with
great earthquakes, at some time in the
not too distant past.
This would explain, it is pointed out,
the great cliff, or escarpment, found by
the Coast and Geodetic Survey scientists.
This is especially true since somewhat
similar feature is suspected off the coast
of Yucatan.