CLASSIFICATION OF MARINE DEPOSITS 



161 



posed, and the processes by which they were accumulated. The 

 classification proposed by Murray and Renard from a study of 

 the great collections of modern marine deposits made by the 

 "Challenger" expedition is as follows: — 



Marine Deposits 



[. Littoral Deposits, be- ] 

 tween high and low ^ 

 water marks. J 



Sands, gravels, muds, 1 

 etc. 



2. Shallow-water Deposits ") 



between low-water I Sands, gravels, muds, 



mark and ioo fath- 

 oms. J 



etc. 



3. Deep-sea Deposits be- 

 yond 100 fathoms. 



f Coral Mud. 

 Volcanic Mud. 

 Green Mud and Sand. 

 Blue Mud. 

 Red Mud. 



Foraminiferal Ooze. ^ jj 

 Pteropod Ooze._^jC^^ 

 Diatom Ooze. • 



Radiolarian Ooze.. 

 Red Clay. 



Terrigenous Deposits 

 formed in deep 

 and shallow water, 

 close to land 



Pelagic Deposits, 

 formed in deep 

 water removed 

 from land. 



The material brought into the sea by rivers, or washed from the 

 shore by waves, is partly mechanically suspended and partly dis- 

 solved ; the former will be 'deposited when the moving water is no 

 longer able to transport it, while the latter is, to a large extent, 

 extracted from solution by the agency of animals and plants, 

 though some of it remains permanently dissolved. The sorting 

 power of water, which is as conspicuous in the sea as in lakes 

 or rivers, arranges the mechanically borne sediments according to 

 the coarseness and fineness of their constituent particles, at the 

 same time effecting a rough separation of the materials accord- 

 ing to their mineralogical composition. Marine deposits are thus 



