SUBMARINE DEPOSITS. 269 
187), and the like, as have not been removed in solution ; only 
the densest bones remaining, around which have formed de- 
posits of manganese (Fig. 188) and iron. Here the rate of 
deposition is at the minimum. After this come radiolarian 
ooze, diatom ooze, globigerina ooze, 
and pteropod ooze, the terrige- 
nous deposits upon the shores of 
the continents accumulating at the 
highest rate. 
Near the shore, in proximity with 
the hundred -fathom line, there is 
undoubtedly held in suspension in 
the water an immense amount of 
decaying organic matter, both ani- 
mal and vegetable, in connection Fig. 188. — Section of manganese 
with the detritus swept into deeper ee AME ee hee 
water from the shores of the con- 
tinental masses; and this probably accounts for the presence 
of glauconite and phosphatic nodules in these areas. At a 
distance from shore, the supply is limited to the dead or- 
ganic matter which finds its way to the bottom,— the re- 
mains of the pelagic fauna and flora. In areas not in the 
track of oceanie currents, or which do not underlie regions where 
pelagic algæ float with more or less regularity, this supply must 
be infinitesimal. 
We owe to Pourtalés the first general sketch of the bottom 
deposits around the eastern shores of the United States. He 
availed himself of the earlier results obtained by Professor 
Bailey from the examination of the deep-sea soundings sub- 
mitted to him by the Coast Survey, and, supplementing these 
by his own observations, he published in Petermann's Journal a 
map of the bottom of the western Atlantic, adjoining the coast 
of the United States. In that memoir he calls attention to the 
main subdivisions of siliceous sand and calcareous deposits, the 
first extending along the eastern coast from New England as 
far south as Cape Florida, and the second around the southern 
extremity of Florida, the Bahamas, and a part of the coast of 
Cuba. 
