ON VOLCANOES AND EARTHQUAKES 373 



phenomena, whatever theory we may adopt for their 

 explanation. We cannot but suppose that operations 

 so important are all dedicated to one great end. And 

 the views of the origin of the unstratified rocks given 

 in this work, being just, it is easy to see what that 

 office is, of which Volcanoes form a part, or of which, 

 at least, they are the proofs and living records. Suc- 

 cessive eruptions of granite and antient porphyry, the 

 same successions in Trap rocks, the elevations of 

 Italy, those of the Coral islands, JEtna and Jorullo, 

 this is the chain, and it is entire. 



The resemblance between many of the trap rocks 

 and the volcanic productions, has been here established ; 

 and these are strongest when we compare the most 

 antient of the volcanic rocks with the former. A very 

 perfect resemblance in all the essential circumstances 

 has been also shown to hold between the trap rocks 

 and those of the granite family. If all this be con- 

 ceded, the whole of these are parts of one great Vol- 

 canic system, operating at different periods and under 

 different circumstances, from the very commencement 

 of the earth to our own days. Under such variations, 

 modern volcanoes may be destined to form future 

 trap rocks: even now they are probably forming be- 

 neath the sea, and, possibly also, beneath the land, pro- 

 ductions of the same nature, as they are also producing 

 islands above it. Our own traps, and even our gra- 

 nites, must then also be the produce of antient volcanic 

 fires ; differing in numerous circumstances which it 

 cannot now be necessary to repeat. Many of these 

 effects may have been purely submarine, lifting with 

 them the strata which now form the earth's surface. 

 Where they have broken through the strata, as they 

 have so often done, it is easy to understand how, in 

 the lapse of time, all the peculiar appearances which 



