258 J. Murray on Sea-bottom Deposits. 
(6) Gray Muds and Sands.—Near volcanic islands we have 
found that the deposits have a distinctive character, from the 
presence of the débris of volcanic rocks. The presence of pieces 
of pumice, scoria, ete., prevents this deposit having that clay 
character so characteristic of the blue mud. The coloris gener- 
ally gray, but occasionally is a black sand or a more or less 
slate-colored mud. In some places the shells of oceanic organ- 
isms make up a large part of these muds. 
own to about fifteen hundred fathoms we have Pteropod, 
Heteropod, and surface Gasteropod shells, and the shore forms of 
Foraminifera are common. Deeper than 1500 fathoms, Pteropod 
from this place, the dredge brought up a great quantity 0 
Gorgonoid axis deeply imbedded in or coated with this blac 
oxide of manganese. : 
In some localities this deposit extends to a great distance 
from the islands, as at Hawaii, 200 miles or more. 
The following are the depths of the soundings which we have 
classed as 
Gray Mud. 
fms. fms. fms fms. fms. fms. ims. 
670 7 1000 260 20to 100 2150 2650 
1150 640 1125 360 75 = «-2600.—Ss«1525 
930 1750 1070 1100 520 1050 420 
5 
1500 620 «41 0 630 500 ni 
278 1890 1675 (?) 150 600 2050 oak 
630 1525 465 600 1200 2875 6 
560 450 
Occasionally a few casts of the Foraminifera have bee 
served of ared color. These were usually very rough, a0 
ganisms of a pale straw-color. None of the glaucon 
were noticed in the same sounding or _ “ posit 
(ce) Red Mud.—tIt has already been stated that the 
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