Atlantis of Plato may have been confined to the "Dolphin Ridge" of our
map.

ANCIENT ISLANDS BETWEEN ATLANTIS AND THE MEDITERRANEAN, FROM DEEP-SEA
SOUNDINGS

The United States sloop Gettysburg has also made some remarkable
discoveries in a neighboring field. I quote from John James Wild (in
Nature, March 1st, 1877, p. 377):

"The recently announced discovery by Commander Gorringe, of the United
States sloop Gettysburg, of a bank of soundings bearing N. 85 deg. W.,
and distant 130 miles from Cape St. Vincent, during the last voyage of
the vessel across the Atlantic, taken in connection with previous
soundings obtained in the same region of the North Atlantic, suggests
the probable existence of a submarine ridge or plateau connecting the
island of Madeira with the coast of Portugal, and the probable subaerial
connection in prehistoric times of that island with the south-western
extremity of Europe." . . . "These soundings reveal the existence of a
channel of an average depth of from 2000 to 3000 fathoms, extending in a
northeasterly direction from its entrance between Madeira and the Canary
Islands toward Cape St. Vincent. . . . Commander Gorringe, when about
150 miles from the Strait of Gibraltar, found that the soundings
decreased from 2700 fathoms to 1600 fathoms in the distance of a few
miles. The subsequent soundings (five miles apart) gave 900, 500, 400,
and 100 fathoms; and eventually a depth of 32 fathoms was obtained, in
which the vessel anchored. The bottom was found to consist of live pink
coral, and the position of the bank in lat. 36 deg. 29' N., long. 11
deg. 33' W."