Affinity between Bafaltes and Granite . 67 
chains have a totally different form from the common conical 
fhape of volcanos or heaps of loofe eje&ed matters. They 
feem to afford a clear inftance of the manner in which long 
continuations of mountains have been elevated ; for it is not 
eafy to admit the fuppofition of the obferver, who has fo accu- 
rately defcribed them, that the iimeftone has been converted 
into lava ; and that the ridges exifted, fuch as they appear at 
this day, before this change was produced by fubterraneous 
Are. Chemical and mechanical confederations are unfavourable 
to this hypothecs; and “ fince moft of thefe branches, whether 
marine, volcanic, or mixed, preferve nearly the fame exter- 
{i nal characters, dire&ions, and parallelifm it appears highly 
probable, that they have not pre-exifted as hills in another 
Hate, but owe their elevation to the expanfive force of fire; 
and that the fame lava which appears in fo many places lies 
alfo under all the Iimeftone hills, of which indeed there are 
evident indications. 
Several modern travellers have defcribed the ftrata of granite 
mountains ; but neither in their defcriptions nor drawings have 
I been able to find fatisfaftory evidence of this arrangement ; 
nor have I obferved it in nature. A liquid mafs fwelled by 
heat muft crack in cooling. Granite feems to me to have 
cracked moft frequently like the bafalte en tables ; and thefe 
flat maffes have been taken for ftrata. A ftratum, confiding of 
proper materials to form whinftone or granite, may have 
been expofed to the neceffary degree of heat, and poffibly have 
undergone this change without much relative local derange- 
ment. Should fuch a ftratum be difcovered, it would afford 
no proof of the {^ratification of the great mountains of granite 
or fhapelefs whinftone, which, in confequence of its nu- 
K 2 
merous 
