Globigerina 

 ooze. 



f^^^ 



Fig. 138.— Globigerina Ooze. 



Station 162, Southern Ocean, lat. 43° 44'. 4 S. 



Valdivia 



long. 75" 33'- 7 E. 



1878 fathoms (magnified). 



164 DEPTHS OF THE OCEAN 



the shells of all these species may occur in the Pteropod ooze, 



but the extent of this 



type of deposit is not 



great. Shelled ptero- 



pods, except Lijuacina, 



are not found in the 



polar oceans. 



Globigerina Ooze. — 

 The average depth of 

 the ocean is about 2000 

 fathoms, and the most 

 widely distributed of 

 the deposits in these 

 average depths is Glo- 

 bigerina ooze (see Figs. 

 137 to 139), which is 

 made up largely of the 

 dead shells of surface 

 foraminifera, the genus 

 Globigerina often 

 greatly predominating, 

 hence the name. About 

 twenty species of pelagic 

 foraminifera (see p. 172) 

 inhabit the surface 

 waters of the tropical 

 oceans, and their dead 

 shells are found in the 

 Globigerina ooze ^ and 

 also in the Pteropod 

 ooze, but towards the 

 Arctic and Antarctic 

 regions only one or two 

 dwarfed species occur 

 in the surface and sub- 

 surface waters. I n very 

 deep water, even within 

 the tropics, the calcare- 

 ous shells do not accu- 

 mulate on the bottom, 



1 The names " Biloculina clay" and ." Orbulina ooze" will lie found in the literature of 

 marine deposits, but these have been described from samples which had been passed through 

 fine sieves, the larger shells having been retained while the smaller ones had passed through 

 the meshes. 



Valdivia ' 

 long, 



Fi<;. 13M. 1,1^ 'i.^.ij i\ > I )ozE. 

 Station 154, Southern Ocean, lat. 6 

 61° 15'. 9 E. , 1940 fathoms (magnified). 



45'.2 S. 



