CHAPTER XII. 



EARTHQUAKES AND VOLCANOES. 



All the natural agents described in the last three chapters, 

 however much they may differ among themselves, agree in 

 this — that they are, upon the whole, slow and certain agents 

 of destruction. Rain and river, frost and thaw, wind and 

 wave — all work in the same direction, persistently attacking 

 the solid land and sweeping away its superficial substance. 

 Not that a particle of this substance is annihilated. Every 

 grain stolen from the land is sooner or later carefully depo- 

 sited somewhere in the sea. But, still, this gradual transfer- 

 ence of matter, from land to water, must ultimately result 

 in the lowering of the general level of the land to that of 

 the sea by the action of the rain and rivers; and, in the 

 subsequent paring down of the plain, thus formed, to the 

 depth at which marine denudation becomes insensible. If, 

 therefore, no hindrance were offered to the action of these 

 agents, not only would a time come when every foot of the 

 British Isles would be buried beneath the sea ; but, inasmuch 

 as the volume of the sea is very much greater than that of 

 the land which rises above the sea-level, if sufficient time 

 were granted, all the dry land in the world would ultimately 

 disappear beneath one universal sheet of water. 



