238 
THE VOYAGE OF H.M.S. CHALLENGER. 
The residue of the Green Muds, after the removal of the carbonate of lime, ranges 
from 43‘82 to 100 per cent., the average being 74’48 per cent., and is of a distinct green 
colour. 
The siliceous organisms range from 1 to 50 per cent., the average being 13‘67 per 
cent., and consist of the remains of Diatoms, Eadiolaria, Sponge spicules, arenaceous 
Foraminifera, and the glauconitic casts of the calcareous organisms.^ 
The mineral particles range from 1 to 80 per cent, of the whole deposit, the average 
being 27 '11 per cent. With the exception of the glauconite grains they are mostly 
angular, varying in diameter from 0'06 to 0*20 mm., the average being 0*13 mm. 
Quartz, monoclinic and triclinic felspars, magnetite, hornblende, and augite are the most 
abundant, but the presence in these Green Muds of tourmaline, zircon, and garnet is 
very characteristic, and we may say the same of the fragments of continental rocks 
which are also very frequent.^ It may be noticed that in the Green Sands there are 
frequently nodules and smaller concretions of phosphate of calcium.® 
The fine washings vary from 9 '69 to 84'05 per cent., the average being 33 '70 per 
cent. 
The following table gives the average percentage of minerals and fine washings and 
the average size of the minerals allocated to depth : — 
Under 500 fathoms, . 
From 500 to 1000 fathoms. 
Over 1000 fathoms, . 
Minerals. 
29 '60 per. cent. 
26*16 
17-50 
9J 
Size. 
0'145 mm. 
0'126 „ 
O'lOO „ 
Fine Washings. 
24*17 per cent. 
44*89 
47*76 
99 
99 
It will be seen that the percentage of minerals and the size decrease with increase of 
depth, while the percentage of fine washings increases. 
In the dredge pumice was obtained in two cases, pebbles in one, and hardened pieces 
of the bottom in one case. 
The following shows the average composition of the Challenger samples of Green 
Mud 
/ Pelagic Foraminifera, .... 14‘59 
Carbonate of lime, Bottom-living Foraminifera, . . . 2 94 
( Other organisms, ..... 7‘99 
2552 
Residue, 
f Siliceous organisms, 
y Minerals, . 
( Fine washings. 
13-67* 
27-11 
33-70 
74-48 
100-00 
* See PI. XXV. « See PI.* XXVI. * See PI. XX. fig. 1. 
* The larger nunil>cr of oiliceouB organifiniH compared with these in Blue and Red Muds (see pp. 232 and 235) is 
due to the glauconitic caste of the Foraminifera. 
