ABYSSAL DEPOSITS 



677 



2,600 fathoms. It contains much volcanic debris, besides the bones 

 of mammals, zeolitic crystals and spherules of extra-terrestrial ori- 

 gin. As already noted, the solution of the pelagic shells in deeper 

 water liberates a minute quantity of such red clay, but a consid- 

 erable part also appears to be derived by decomposition of volcanic 

 dust. The clay is. generally rich in Radiolaria ; indeed these have 

 been regarded as forming merely a phase of the red clay deposit of 

 the deep sea, they seldom if ever occurring quite pure. 



Analyses of Deep-Sea Deposits. 



The following analyses quoted from Clarke (2oa-^j(5) give (a) 

 the composition of the red clay from 23 analyses. Others have 

 given a carbonate of lime content as high as 60 per cent. Added to 

 this are analyses of (b) radiolarian ooze, (c) diatom ooze, (d) 

 Globigerina ooze, average of 21 analyses, (e) Globigerina ooze very 

 high in carbonate, and (f) pteropod ooze. All samples dried at 

 110°. Soluble and insoluble portions in analyses a, b and d are not 

 separated in the table. 



Table of Analyses of Deep-Sea Deposits. 



Red clay 



b 

 Radio- 

 larian 

 ooze 



c 



Diatom 

 ooze 



d 

 Globi- 

 gerina 

 ooze 



e 

 Globi- 

 gerina 

 ooze 



f 

 Ptero- 

 pod 

 ooze 



Ignition 



SiOa 



AI2O3 



FesOa 



MnOa 



CaO 



MgO 



CaCOa 



CasPsOg 



CaS04 



MgCOs 



Insoluble*. . . . 



450 



62. ID 

 16.06 

 11.83 



0.55 

 0.28 

 0.50 

 0.92 



o. 19 



0.37 

 2.70 



530 

 67.92 



0-55 

 0.39 



19.29 



0.41 

 0.29 



113 

 4.72 



7.90 

 31 71 



II . 10 



703 



trace 

 0.41 

 o. 12 



3751 

 2.80 

 0.29 

 113 



100.00 



2.00 

 3-65 

 0.80 

 3.06 



82.66 

 2.44 



0.73 

 0.76 



390 



100.00 



* Contains silica, alumina, and ferric oxide not separated. 



