4 MICROSCOPICAL OBJECTS FOUND 



limestones on an extended scale, was open to 

 the same objections as the preceding one. 



These explanations not being considered satis- 

 factory, another view was propounded, and 

 received by many as sufficient to account for 

 most of the phenomena presented by calcareous 

 rocks. It was supposed that the waters of the 

 ocean contained large quantities of lime in solution, 

 and that in the deeper seas, where undisturbed by 

 local currents produced along the coasts, a slow 

 chemical decomposition took place, causing the 

 precipitation of an insoluble carbonate of lime.* 

 To account for the existence of lime in the sea, 

 submarine volcanoes and volcanic springs were 

 had recourse to ; it being supposed, not without 

 reason, that such springs did from time to time 

 discharge large quantities of calcareous matter 

 into the ocean .f 



Faint glimpses of another hypothesis had been 

 obtained by a few authors. Early in the eighteenth 

 century, Soldani had collected, from less than an 

 ounce and a half of stone from the hills of 



* Encyclopaedia Metropolitana. Article, Geology, pp. 544 

 and 656. 



t Lyell's Principles of Geology. Vol. iii. p. 240. 



