516 
THE DEPTHS OF THE SEA. (CHAP. X. 
from granite; the largest of the two fragments weighed 
15 grains. 
5 Quartz, milky in colour or colourless ; the largest of these 
weighed 90? grains, and showed evidence of having been 
derived from the quartz-veins so common in clay-slate. 
19 Fragments of true volcanic lava, most of which were very 
2 
OC 
light and scoriaceous (vesicular), although some small 
ones were compact and erystalline; and in these the 
minerals augite, olivine, and glassy felspar (Sanadine) 
could be distinetly recognized. Among these were frag- 
ments of trachytic, trachydoleritic, and pyroxenic 
(basaltic) lavas, quite similar to those of Iceland or Jan 
Mayen of the present period, from which they had 
probably been derived. 
GRAVEL FROM 1,443 FAaTHOMS (STATION 20). 
This sample of gravel consisted of 718 subangular fragments, 
in general not above from 4 to } grain in weight, with occasion- 
ally some of a little greater size; but the most considerable of 
all (a fragment of mica schist) only weighed 3 grains. They 
consisted of :— 
2 
+ 
St 
SLi 
273 
Fragments of orthoclase felspar. 
Bituminous or carbonaceous shale (? if not accidental). 
Fragments of shell (undistinguishable species). 
Granite, containing quartz, orthoclase, and muscovite. 
Grey compact limestone. 
Quartzose mica schist. 
Hornblende schist ; sometimes containing garnets. 
Quartzite fragments, with a very few fragments of clear 
quartz. The majority of the pieces being of a dirty 
colour, often cemented together, were evidently the 
débris of quartzite rocks or beds of indurated sandstone, 
and not from granite. 
Black compact rock, containing augite, most probably a 
voleanic basalt. 
