‘230 
THE VOYAGE OF H.M.S. CHALLENGER. 
Amoug the Challenger deposits described in the Tables of Chapter II. there are 
58 examples of Blue ]\Iud. These range from 125 to 2800 fathoms, the average depth 
l)cin£ 3 : 1411 fathoms. 
O 
12 ai’e from depths less than 500 fathoms. 
6 
» 
from 
500 to 1000 
if 
15 
if 
i> 
1000 „ 1500 
» 
6 
» 
)i 
1500 „ 2000 
a 
20 
» 
if 
2000 „ 2500 
if 
9 
» 
over 
2500 
a 
27 of these examples are called blue-grey in colour, and 18 grey. 
The carl)onate of lime ranges from the merest trace in 2650 fathoms and lesser depths 
to 34’34 per cent, in 500 fathoms, the average being 12*48 per cent. This would seem 
to indicate a gradual decrease in the quantity of carbonate of lime with increase of 
depth, as in the case of purely pelagic deposits, but arranging the percentages in groups 
of 500 fathoms, it will be seen that there is a marked departure from this rule, as might 
indeed be expected, considering the varied origin of these coast deposits and the varying 
amount of river detritus and oro^anic remains in different situations. 
O 
Under 500 fathoms, 
From 500 to 1000 „ 
„ 1000 „ 1500 
„ 1500 „ 2000 
„ 2000 „ 2500 
Over 2500 ,, 
10‘61 average per cent. CaCOg. 
10-85 
18-94 
9-41 
10-86 
10-53 
Of the organisms which yield the carbonate of lime in these Blue Muds the pelagic 
Foraminifera make up on an average 7*52 per cent., the bottom-living Foraminifera 1*75 
per cent., and other carbonate of lime remains 3*21 per cent. In some cases the pelagic 
Foraminifera make up as much as 25 per cent, of the whole deposit, while in others no 
trace of them can be detected. The bottom-living Foraminifera may make up 10 per cent., 
and, again, the other calcareous remains 16 per cent, of the deposit. The shells of pelagic 
species, which make up so large a part of a Globigerina Ooze, are not abundant nor 
univci’sally distributed in the Blue ]\Iuds, the remains of shallow-water or bottom-living 
organisms predominating in many ca.ses. The organisms most frequently mentioned are the 
shells of Globigerinidm, Rotalidac, Lagenidai, Miliolidae, Textularidm, Nummulinidae, Lamel- 
libranchs, Gasteropods, Ostracodes, Echinoderm fragments, Coccoliths, and Rhabdoliths. 
The residue left after treating the deposits with dilute hydrochloric acid is chiefly 
brown f)r grey ; in 19 ca.ses it was a shade of l)rown, in 15 a shade of grey, in 7 it was 
green, and in 5 it was blue. In 9 cases there was no carbonate of lime or only traces, 
and con.scqucntly no residue apart from the deposit itself. The mean percentage of 
