46 



reflection, before he could account for them; which he does, 

 at hist, by considering the suite of degi^adations, and the de- 

 composition, by Avhich so many materials had been carried off. 



I must confess, it is not surprising, that Mr. Desmarest 

 should be much puzzled at finding a material, which, ac- 

 cording to his theorj', must have been in an high state of 

 fluidity, settling itself on the summits of hills; yet tliis is a 

 situation, for which columnar basalt seems to have a strong 

 predilection, as well in Vivarois, and the North of Ireland, 

 as in Auvergne. 



These difficulties, Mr. Desmarest has been able to eet 

 over, at least, to his own satisfaction, without giving up his 

 theory. With others, he is not equally fortunate : he tells us, 

 page 720, that he found prismatic masses, qui ne tienncnt a 

 rien, which, by their disposition, exclude all correspondence 

 with currents of lava, or with volcanos. These, he says, we 

 are under the necessity of supposing, were fused and cooled 

 on the spot. 



Here Mr. Desmarest admits, that his theory does not ac- 

 count for the formation of all columnar basalts. Some, he 

 confesses, are out of the reach of volcanos; and he is under 

 the necessity of inventing a new operation of nature for the 

 purpose. And, since it is plain, on inspection, that fluid 

 lava could not have travelled to the place Avhere he found 

 these basalts, he is obliged to fuse something, on the spot, for 

 his purpose; without condescending to give us the shghtest 

 account of these new and occasional fires, or of any circum- 

 stance attending them. 



Mr. 



