OOLITIC ROCKS. 107 



result is a compact and homogeneous rock. Wlien, 

 however, the water thus charged rises from a slight 

 depth, or at a point where it is subjected to tlie in- 

 fluence of marine currents, the matters already de- 

 posited are so tossed about that they present all 

 their surfaces to the petrifying action. The in- 

 crustation thus caused deposits itself all around them 

 in concentric layers ; and their final combination, or 

 massing together, causes them to resemble a heap of 

 little eggs. The aggregation of all these oolitic par- 

 ticles by the incrusting matter does not completely 

 deprive the deposit so formed of its primitive cha- 

 racter, and it is accordingly named oolite (or stone 

 formed of eggs). The structure of this kind of rock 

 has been called by geologists, Oolitic. 



The submarine deposits resulting from Geyserian 

 action are of much less importance than those which 

 are due to mechanical sedimentation. The physical 

 forces play only a special part in their production. 

 The life of the globe is the cause of numerous mo- 

 difications in the aspect of the submarine soil, and 

 in the nature of the deposits which accumulate at 

 the bottom of the Ocean. Independently of the re- 

 mains of terrestrial animals and plants which are 

 borne into the sea, and swept through its depths by 

 marine currents, or rolled by the waves, innumerable 

 creatures live in the sea itself, and enrich it witli 



