74 BULLETIN OF THE 
tendent of the Coast Survey, in running a number of lines normal to the 
coast, south of Cape Hatteras and north of the Bahamas, and extending 
them into deep water. Commander Bartlett has sent his Report to 
Professor Hilgard, the Superintendent of the Coast Survey, who has 
kindly allowed me to make use of these results in connection with my 
present work on a general report of the dredging expeditions of the 
“Blake.” ‘The accompanying map has kindly been prepared for my use 
by the Superintendent of the Coast Survey.* 
As was to a certain extent anticipated, the lines show the existence 
of an extensive plateau, of a triangular shape, reaching from the Bahamas 
to immediately south of Cape Hatteras, where this plateau gradually 
passes into the continental plateau, extending northward, which is lim- 
ited by the 100 fathom line, and has a steep slope extending to deep 
water, 
The eastern edge of this plateau is from 300 to 350 miles from the 
coast, and forms a gigantic submarine plateau, with an abrupt slope 
passing into deep water. For the sake of brevity I shall call this 
plateau the “ Blake plateau.” The eastern edge of the slope of the 
Blake plateau commences at an average depth of at least 400 fath- 
oms, so that the general profile of the lines extending normally across 
the Blake plateau show a gradual incline from the shore to a depth 
of about 50 fathoms, then a somewhat abrupt slope to a depth of about 
400 fathoms, then a very gradual descent to the edge of the sharp, steep 
slope forming the outer eastern edge of the Blake plateau, at a depth 
of nearly 600 fathoms. 
It is interesting to speculate how this peculiar profile, so different 
from that of any other part of our coast, was formed. The explanation 
to my mind is comparatively simple. The present outer eastern edge 
of the Blake plateau, which is now at a depth of 600 fathoms, was 
at one time at a much higher level. In fact, I assume that this slope 
* These lines have, during the season of 1882-83, been extended south of the 
Bahamas as far as Porto Rico. Under the direction of Professor Hilgard, the 
“Blake,” in command of Lieutenant-Commander Browson, U. 8. N., ran normals 
into deep water, showing that the great submarine Bahama plateau developed by 
Commander Bartlett commences slightly to the westward of Great Abaco, and 
extends thence northward, as is shown on the accompanying map. Lieutenant- 
Commander Browson showed further that to the south the eastern edge of the 
Bahama Bank extended but a short distance seaward parallel to the general line 
of the outer row of islands of the group, till it united with the great plateau upon 
which Porto Rico and the Caribbean Islands crop out, leaving probably one or two 
deep passages extending towards the old Bahama Channel north of San Domingo 
and Cuba, leading to the Windward Passage. 
