Notice of Active and Extinct Volcanos. 89 



now only local, and occasional. It is however obvious, that 

 this intense action would set bounds to itself ; and that the 

 chemical combinations would cease, when the crust of in- 

 combustible matter thus formed, had become sufficiently 

 thick and firm, to protect the metals and combustibles, from 

 the water and the air, and other active agents. 



As we are not giving a theory of the earth, but merely 

 stating the conditions of a problem, we forbear to descant 

 upon many obvious collateral topics, or to pursue the vari- 

 ous rock formations, through the vicissitudes which might 

 have attended them.* We do not even undertake to say, 

 that we believe that such events as we have endeavored to 

 describe, did actually happen ; we say only, that their exis- 

 tence is consistent with the known properties of the chemi- 

 cal elements, and with the physical laws of our planet. Sup- 

 posing that such was the actual progress of things, it is obvious 

 that the oxidated crust of the globe, would still cover a nucleus 

 consisting of metallic and inflammable matter. Of course, 

 whenever air and water, or saline and acid fluids, might 

 chance to penetrate to this internal magazine, the same vio- 

 lent action which we have already supposed to have happen- 

 ed upon the surface, would recur, and the confinement and 

 pressure of the incumbent strata, increasing the effects a 

 thousand fold, would necessarily produce the phenomena of 

 earthquakes and volcanos. 



Still, it is equally obvious, that every recurrence of such 

 events, must oxidize the earth deeper and deeper, and if the 

 point should ever be attained, when water or air ceased 

 to reach the inflammable nucleus, the phenomena must 

 cease, and every approximation towards this point would 

 render them less frequent. 



Does this correspond with the actual history of these 

 events ? Are they now less frequent, than in the early ages 

 of our planet ? The answer to this question must depend so 

 much upon the theoretical views entertained of the forma- 

 tion of granite, and of the other primitive rocks, that it may 

 be impossible, at present, to bring it to a decision. 



Whatever we may think of the hypothesis now detailed, 

 and which we suppose to coincide substantially with the 

 views of our author, may we not suppose, with sufficient pro- 



* The present hypothesis does not exclude the subsequent action of water, in 

 dissolving chemically, or disintegrating mechanically, the crust of the globe. 



Vol. XIV.— No. 1. 12 



