On the Declivities of Mountains. 37 



thefe latter are covered with the fame beds of gneifs, &c. as 

 the northern fides of the Saxon, and thereby are rendered 

 fmooth and gentle comparatively to the oppofite fide, which, 

 being fhehered, remains deep and abrupt; which explains* 

 the feventh observation. 



The caufes here afiigncd explain whv the covering; of ad- 

 ventitious ftrata on the higheft mountains is generally thin- 

 ner!: at the greateft height, and thickeft towards the foot, of 

 the mountain ; for the bulk of the water that contained the 

 adventitious particles being proportioned to its depth, and 

 the mafs of earthy particles with which it was charged being 

 proportioned to the bulk of water that contained them, it is 

 plain, that as the height of water gradually decreafcd, the 

 depofitions from it on the higher parts of the mountains 

 muft have been lefs copious than on the lower, where they 

 muff have been oftener repeated. 



Fence, 3°, granitic mountains, generally the moft antient, 

 frequently have their northern or eaftern fides covered with 

 ftrata of gneifs or micaceous fchiltus, and this often with 

 argillite, or primeval fandftone or limeltone, thefe being 

 either of fomewhat later formation, or longer iufpendibie in 

 water. 



Hence, 3 , different fpecies of ftone are often found at dif- 

 ferent heights of the fame flank of a mountain, according as 

 the water which conveyed thefe fpecies happened to be dif- 

 ferently impregnated at different heights : during the firft -rra 

 its depofitions formed the primitive (tony maffes ; but after 

 the creation of fifh, limeltone, fandftone, farcilites, and fe- 

 condary argillites, in which pifcine remains are found, were 

 depofited. But, during the fecond sera, viz. that of the Noa- 

 chian deluge, by reafon of the violence and irregularity of its 

 arrgreffion, the depofitions were more mifcellaneous, and are 

 found at the greateft heights; yet, in general, they may well 

 be diftinguifhed by the remains of land animals or of veue- 

 tables, or of both, which they prefent in their ftrata (01 at 

 leaft by the impreffions of vegetables which thev hear), as 

 thefe muft have been conveyed after the earth had been in- 

 habjted. But mountains regularly ftratified bearing fuch re- 

 mains, 



