DEEP-SEA EXPLORATION. 
403 
Ai'erafje composilioii of Hn' Clialli iu/ci' sampler of rolcanic mmi and volcanic sand. 
Volcauic mud. 
Volcanic sand. 
(’arbonate of lime: 
Pelagic foraminifera 
1(1. 50 
2. H2 
7. 17 
13 
3. 80 
11.00 
*>s 7n 
Residue : 
1.H2 
•10. 82 
30. 87 
l.-lo 
00 
0. 81 
71 ‘>1 
100 
100 
10. Coral mad and sand. — Just us aroimd volcanic islands tbe deposits arc principally made up of 
tlio d6bris from volcanic rocks, so olf coral islands and coral reefs tbo deposits are cliielly made up of 
the fragments of organisms living in the shallow Avaters and on the reefs, siicli as calcareous alga*, 
corals, molliisks, i)olyzoa, annelids, echinoderms, and foraminifera. These fragments form a coarse 
sand or gravel in the shallower Avaters, but beyond the limits of Avave action there is a line nuid, 
consisting principally of triturated particles of calcareous matter. With greater dei)th and increasing 
distance from the land, pteropod and heteropod shells, as Avell as ]>elagic foraminifera, make uji more 
and more of tbe deposit, till the coral muds and sands pass finally into a pteropod or globigerina ooze, 
in Avhich reef fragments can with difficulty be recognized. 
The C/(rtRc»ycr samples of coral mud ranged in depth from 140 to 1,8130 fathoms, the aA'erage being 
740 fathoms. The samples of coral sand Avere all in depths less than 300 fathoms, the average 
being 176 fathoms. The i>ercentago of carl)onato of lime is A ery high, in some cases over 00 ]>er cent, 
principally duo to the remains of pelagic and bottom-living foranunifera, though the remains of other 
calcareous organisms derived from the reefs are much more abundant than in any of the other types 
of deep sea deposits. Siliceous organisms are more abundant in the sands than in the muds, oAving 
to the smaller quantity of minute clayey and calcareous amorplious matter, consisting of sponge 
sjiicules, diatoms, and radiolaria. Mineral particles are rare in both varieties, consisting of feldspar, 
augite, etc. 
Arcraije voniposition of the Challviujer samples of coral mad and coral sand. 
Coral mud. 
Coral saiul. 
Carbonate of lime: 
Pelagic foraminifera 
31. 37 
36. 25 
Hottomdiving foraminifera 
U. W 
20 
Otlier organisms 
39. 62 
30. 59 
Residue : 
85.33 
86. 84 
Siliceous organisms 
1.36 
5 
1 
Fine washings 
12. 11 
4.41 
14.47 
100 
13. 1(3 
100 
