FOSSIL FORAMINIFERAL OOZES 



453 



one. being in round numbers 105 million square kilometers or 29.2 

 per cent, of the entire oceanic surface (Krummel-57 : /^5*). Its 

 principal distribution is, however, in the Atlantic Ocean, where it 

 occupies more than 44 million square kilometers, overshadowing all 

 the other deep-sea sediments. In the Indian Ocean 31 million 

 square kilometers of bottom are covered by this deposit, but in the 

 Pacific it covers only 30 million- square kilometers, a comparatively 

 small percentage of the bottom of that ocean. 



Fossil Foraniiniferal Ooccs. Typical foraminiferal oozes are 

 found in fossil form mainly in the chalk of the west of Europe and 



Fig. 105. Globigerina ooze, x 20. (After Murray and Renard.) 



elsewhere. Deposits of foraminiferal shells, of large benthonic 

 types, are, however, developed in other horizons. Such are the Fu- 

 sulina limestones of the Carbonic and Permic, and the Nummulite 

 and Orbitoidal limestones of the Tertiary. These are best classed 

 as shell rocks. Chalk, on the other hand, is a distinct foraminiferal 

 ooze, a calcipulverite, but, unlike the Globigerina rock, it is not 

 formed of pelagic, but of benthonic or bottom types. (Fig. 106.) 

 Among these the biserial Textularia holds the same position that 

 Globigerina does in the modern deposit, while another benthonic 

 form, Rotalia, is also common. Pelagic forms, however, are not 

 wholly absent, nor should we expect them to be. Nineteen species 

 have been recognized as found both in the modern Globigerina ooze 

 and the Cretacic chalk, but this identification of species is largely 

 due to the lack of distinctive characteristics. Coccoliths also are 



