Ei^perimenii on Whinflone and Lava, 6 1 



So clofe a refembbnce affords a very (trong prefumption in favour of Dr. Hutton's fy- 

 ftem, according to which both clafles are fuppofed to have flowed by the aftion of heat ; 

 but the circumftances under which they were expofed to this adlion being materially dif- 

 ferent, we have reafon to look for indications of that difference. Such are nftt wanting. 



Calcareous fpar frequently occurs in whinftone, eitlier in veins or in detached nodules, 

 but is never found in Java, and could not exift in a volcanic ftream ; for heat, in fuch cir- 

 cumftances, would infallibly drive off the carbonic acid, and compel the lime to unite with 

 the other component elements of the mafs. In whinftone, which Dr. Hutton fuppofes to 

 have flowed, at fome remote period, in crevices of the earth, at a great depth below what 

 was then its furface, the weight and ftrength of the fuperincumbent mafs of ftrata*has 

 been fufficient to rcfift the expanfion of the carbonic acid, and to conftrain it, upon the 

 principle of Papins digefter, to continue in combination with the lime. This compound 



have called the liver cryftallite, and is probably formed in the fame manner. I have feen a mafs pofleffing, 

 in a great meafiire, the ftony charaflcr of whins and lavas, which was produced in a lime-kiln by th^ 

 fufion of an impure limeftone ; and Dr. Beddoes has obferved a cryftallized texture in the flags of fome iron 

 furnaces. I am informed, that the celebrated Mr. Klaproth has ds-fcribed fome ftriking examples of cry- 

 ftallization after fufion, which he obtained in expofing various fubftances to the heat of the porcelain fur- 

 nace at Berlin. 



* It may be aflced, what has become of this fuperincumbent mafe ; and by what means it has been re- 

 moved. Dr. Hutton anfwers, that it has been gradually worn away during an immenfe courfe of ages, by 

 the aSlion of thofe caufes which continue, under our eyes, to corrode the furface of the globe : that the 

 folid parts, being conveyed to the bottom of the ocean, are there depofited in beds of fand and gravel, 

 which, in fome future revolution, being expofed to heat, may be again converted into ftony ftrata. 



The whole of this fyftem appears to me well founded, except in what regards the removal of the fuper- 

 incumbent mafs, which has been performed, I conceive, in a very different manner. I am inclined to 

 agree ou this point with M. Pallas, M. de Sauflure, and M. Dolomieu, and to believe that, at fome 

 period very remote with refpeft to our hiftories, though fubfequent to the induration of the mineraj.jcing- 

 dom, the furfaoe of the globe has been fwept by vaft torrents, flowing with great rapidity, and foxleep as 

 to overtop the mountains ; that thefe torrents, by removing and undermining the ftrata in fome places, 

 and by forming in others immenfe depofits, have produced the broken and motley ftruflure, which the 

 loofe and external part of our globe every where exhibits. 



In the Alps and in Sicily I have witncffed feveral of thofe curious fafts, upon which M. de Sauflure 

 and M. Dolomieu found their opinion, and which feem to juftify their conclufions. I have likewife *tib- 

 ferved, in this country, many phenomena which denote the influence of fimilar agents. Lord Daar, who 

 joins me in agreeing with Dr. Hutton in almoft every article but this, has added great weight to the ar- 

 gument by fome general obfervations on lakes, and by fome very interefting fafts which he has obferved 

 in the Highlands of Scotland. We propofe to purfue this fubjeft, and to lay the refult of our inquiries 

 before the fociety. Dr. Hutton, in the fecond volume of his Theory of the Earth, has taken great pains^o 

 refute all that has been faid about thefe torrents; but, in my opinion, their exiftence is not only quite 

 confiftent with his general views, but feems deducible from his fuppofitions, almott as a neceflary confe- 

 quence. When the ftrata, according to his fyftem, were elevated from the bottom of the fea, the. removal 

 of fo much water, if not performed with unaccountable flownefs, muft have produced torrents, in all di- 

 rcftions, of exceflive magnitude, and fully adequate to the effefts I have thus afcribed to them. 



feems 



