44^ 



" fcrved fo frefli ia this unalterable material, that to look at tlieiTi, 

 " one would fufpeft that the work had been fufpended only yefterday." 

 [Travels, chap. 17.] 



The decompofition of Bafalt rocks, feems more queflionable. I know 

 that both the plain fides of prifms, newly expofed to the air, and alfo 

 all recent fractures, very foon acquire a fort of ruft, well accounted for by 

 Mr. Playfair, who fays, " by the aftion of air and moillure, the iron 

 " becomes oxydated in fuch a degree, as to lofe its tenacity, fo that 

 " the texture of the furface is deflroyed." I ftrongly fufpeft this de- 

 compofition has its limit, and that this ruft forms a fort of pafte on the 

 furface of the ftone, which protefts it from farther injury. I never faw 

 a bafalt pillar, which had the appearance of having fuffered any dimi- 

 nution, farther than a flight blunting of its angles ; the articulations 

 too, fuffer a little, and the points or pyramids which afcend from the 

 lower joint often fall down, but all pillars of the mod ancient expofure, 

 feem to preferve their original diameters. 



The more general account of the ftate of our world, as given by 

 both Dr. Hutton and Mr, Playfair, is very alarming. The latter afferts, 

 that, " a fyllera of univerfal degradation, and decay, may be traced over 

 " the whole furface of the land, from the mountain top to the fea- 

 " fliore" J and, " that water from the fmallefl: rill to the greatefl: river 

 " attacks whatever has emerged above the level of the fea, and la- 

 " hours inceflantly to reftore it to the deep." (page 99, 100.) 



Mr. Playfair fuppofes a geologift; fuddenly tranfported " into alpine 

 *' trafts, where the furface of the earth attains its greateft elevation," 

 and then details the train of his refleftions. 



The firft impreflion on his mind is made by the novelty and mag- 

 nificence of the fpeElacle before him ; he then finds out the caducity of 

 the objefts around him, and like another Xerxes, looking down with a me- 

 lancholy eye upon his innumerable hoft, and weeping when he re- 

 flects on the fliort period of exiftence they have to enjoy, Mr. Play- 

 Jair'% geologift " begins to difcover the footfteps of time, and to per- 



" ceive. 



