16 



INTRODUCTION. 



Fig. 3. Organisms in the Atlanti c Ooze, 

 chiefly Foraminifera (Globigerina and 

 Textiilaria] , with Polycystina and sponge- 

 spicules ; highly magnified. (Original.) 



lantic and Pacific, covering enormously large areas of the 

 sea-bottom, and it presents itself as a whitish-brown, sticky, 

 impalpable mud, very like greyish chalk when dried. Chem- 

 ical examination shows that the ooze is composed almost 



wholly of carbonate of lime, 

 and microscopical examination 

 proves it to be of organic origin, 

 and to be made up of the re- 

 mains of living beings. The 

 principal forms of these belong 

 to the Foraminifera, and the 

 commonest of these are the 

 irregularly -chambered shells of 

 Globigerina, absolutely undistin- 

 guishable from the Globigerince 

 which are so largely present in 

 the chalk (fig. 3). Along with 

 these occur fragments of the 

 skeletons of other larger creatures, and a certain propor- 

 tion of the flinty cases of minute animal and vegetable 

 organisms (Polycystina and Diatoms). Though many of the 

 minute animals, the hard parts of which form the ooze, un- 

 doubtedly live at or near the surface of the sea, others, prob- 

 ably, really live near the bottom ; and the ooze itself forms 

 a congenial home for numerous sponges, sea-lilies, and other 

 marine animals which flourish at great depths in the sea. 

 There is thus established an intimate and most interesting 

 parallelism between the chalk and the ooze of modern oceans. 

 Both are formed essentially in the same way, and the latter 

 only requires consolidation to become actually converted into 

 chalk. Both- are fundamentally organic deposits, apparently 

 requiring a considerable depth of water for their accumulation, 

 and mainly composed of the remains of Foraminifera, together 

 with the entire or broken skeletons of other marine animals 

 of greater dimensions. It is to be remembered, however, that 

 the ooze, though strictly representative of the chalk, cannot 

 be said in any proper sense to be actually identical with the 

 formation so called by geologists. A great lapse of time 

 separates the two, and though composed of the remains of 



