PERMANENCE OF CONTINENTS AND OCEANIC BASINS. 135 
north of Cape Hatteras, and in the Gulf of Mexico, the con- 
tinental line of one hundred fathoms is most plainly marked, 
forming the upper edge of the more or less abrupt descent lead- 
ing into deep water with a regular inclination. Owing to the 
absence of this hundred-fathom line south of Cape Hatteras, 1 
became an interesting problem to trace the exact profile of that 
part of the coast, and to continue it into deep water. The sea- 
son of 1881 was spent by Commander Bartlett in the “ Blake,” 
under the direction of the Hon. Carlile P. Patterson, the late 
Superintendent of the Coast Survey, in running a number of 
lines normal to the coast, south of Cape Hatteras and north of 
the Bahamas, and carrying them into deep water. The Super- 
intendent of the Coast Survey has kindly allowed me to make 
use of the results of Commander Bartlett in connection with 
my report of the dredging expeditions of the * Blake." ' 
As was to a certain extent anticipated, the lines developed an 
immense plateau, of a triangular shape, reaching from the Ba- 
hamas to a point immediately south of Cape Hatteras, where this 
plateau passes into the northern continental shelf, limited by 
the hundred-fathom line. 
The eastern edge of this plateau is from three hundred to 
three hundred and fifty miles from the coast, and with an ab- 
rupt slope passes into deep water. For the sake of brevity I 
shall call it the “Blake Plateau.” (See Figs. 56, 176.) Тһе 
eastern edge of the slope of the Blake Plateau commences at an 
average depth of at least four hundred fathoms, so that the 
general profile of the lines carried normally across it shows a 
gradual incline from the shore to a depth of about fifty fath- 
oms, then a somewhat abrupt slope to a depth of about four 
1 These lines have, during the season | ant-Commander Brownson proved further 
of 1882-83, been extended south of the that to the south the eastern edge of the 
Bahamas as far as Porto Rico. Under Bahama Bank ran but a short distance 
the direction of Professor Hilgard, the seaward parallel to the general line of the 
* Blake," in command of Lieutenant- outer row of islands of the group, till it 
Commander Brownson, U. S. №., гап nor- united with the plateau upon which Porto 
mals into deep water, showing that the Rico and the Caribbean Islands crop out, 
Blake Plateau developed by Commander leaving probably one or two deep pas- 
Bartlett commences slightly to the west- sages extending towards the old Bahama 
ward of Great Abaco, and extends thence Channel north of San Domingo and Cuba, 
northward. (See Figs. 56, 176.) Lieuten- leading to the Windward Passage. 
