78 HIDDEN BEAUTIES OF NATURE 



Wallich gives excellent reasons for supposing the 

 flinty nodules in the chalk owe their origin to sponges 

 (see the chapter on the Euplectella). The opinion 

 that the deep sea globigerina ooze is but chalk now 

 being laid down, and that it in every way corres- 

 ponds with the chalk of the cliffs, as at Dover and 

 elsewhere, is gaining support. 



There are some who even think there has been no 

 break nor interruption in the continuity of the form- 

 ation of chalk from the Cretaceous epoch down to 

 the present time that in fact we are living in the 

 Cretaceous period. Geologists would find it no easy 

 matter to find a line of demarcation between the 

 globigerina ooze and the admittedly true chalk. 



Whether we can reconcile the present with the 

 past, or whether it be utterly impossible, the fact 

 remains, that tiny creatures, the simplest of the simple 

 in structure of sarcode, are now doing a stupendous 

 work on certain ocean floors, and that creatures like 

 them, if not quite identical, possessed of similar 

 powers, secreted carbonate of lime in the remote past, 

 and fulfilling the purposes for which they were created, 

 passed away, leaving their shells to form extensive 

 areas of chalk, hundreds of feet in thickness. 



