CH. Il] THE OCEANOGRAPHY OF THE NORTH-WESTERN OCEAN 35 



Pteropod Ooze, a substance which is characterised by the pre- 

 ponderance of the shells of Pteropods, pelagic Gasteropoda which 

 live at the surface of the sea in great shoals. From about 1000 to 

 3000 metres is the depth of sea in which Pteropod ooze is found, 



Pteropccl^ HeterofDod, and Pelagic foramin ifera shells 



other mclluScan^hells and and worm tubes, PTeK)|Dod 



[Delagic foraminiFera shells Shells., . ^ 



PTero hod Ooze GTobiQerina QQze 



^Ca lca r to us deposits 



Remains of Radiolan'a, 



RadiolQriQn Ooze. 



SILICEOUS 



Frustufes oF diatoms, 

 Spon<q& spicules. 



Diatom Ooze. 

 DEPOSITS 



Fig. 14. Sea bottom deposits. 



outside these limits is the area of distribution of the well-known 

 Globigerina Ooze which is characteristic of a greater extent of 

 ocean bed than any other deep-sea deposit. It is formed of the 



3—2 



