808 THE BOTTOM OF THE SKA. 



SUDDEN MOVEMENTS OF THE SUBiMAKINE SOIL. 



1. Earlhqiialccs modify the Bed of the Ocean — Submarine 

 Volcanoes. 



The bottom of the sea, as well as the surface on 

 which we live, is subject to modifications by the 

 action of earthquakes. They are, generally, accom- 

 panied by submarine volcanoes, which also alter the 

 sea-be \ and cause a displacement of the waters. It 

 is observable, in fact, that volcanoes never display 

 their whole energy except in the neighbourhood of 

 seas or large sheets of water. The existence of sub- 

 marine volcanoes need not then excite astonishment ; 

 it is probable, indeed, that their number is very 

 great, and it is reasonable to attribute to the action 

 of submarine eruptions of which we have no know- 

 ledge, the seismical phenomena that have been ac- 

 companied by no visible volcanic disturbances. 



At the commencement of its activity, subma- 

 rine volcanic action is sometimes signalised by a 

 peculiar agitation of the sea, where the depth is at 



