'44 



receives iiom its other numerous and zealous advocates; and 

 then I Avill proceed to try, whether this opinion be reconcile- 

 able, or not, to the facts in my own basaltic country. 



MR. DESMARESTS MEMOIR. 



Mr. Desmarest states, that, as he travelled through the 

 imountains of Auvergne, he examined the extinguished vol- 

 canos, of which that country is full; and found, that currents 

 of lava had issued from them in such abundance, as to cover 

 a district eight or nine leagues in diameter. He gives us a 

 map of this district, and affects to trace the several currents 

 upon it, with great accuracy. 



'' He observed, that when these currents were broken by 

 mountain torrents, or other causes, the perpendicular face, 

 so laid bare, was often composed of prismatic pillai-s, ge- 

 nerally articulated, and exactly like those of the Giant's 

 Causeway, in Ireland. 



He tells us, also, that he has traced these cuiTents up to 

 the crater itself. 



'From the situations and circumstances, under which Mr. 

 Desnlavest found these pillars, he infers, they were formed 

 by the fluid lava assuming these shapes as it cooled. 



Such are the observations and inference, upon which the 

 whole theory of the volcanic origin of basalt is founded; and 

 it is plain, that, if what Mr. Desmarest pronounces to be 

 currents of lava, are proved to be actually such, his con- 

 clusion is irresistible. 



The 



