452 



Beginning at the mountain ridge, and dcfcending, I boldly fay that we 

 find the valley begun before the rill appears, it being the effed not the 

 caufe of the valley, which, in fuch regions is often very great when 

 the rill is infignificant, and (where the declivity is fmall) infuiEcient to 

 cut a channel for itfelf, but forming a morafs ; it foon acquires quan- 

 tity and velocity enough to form a channel, in which it runs peace- 

 fully at the bottom of the valley, increafing in fize and rapidity ; it 

 now begins to commit fome depredations, undermining occafionally the 

 fide of the valley it runs clofe to, efpecially if it happens to projeft ; 

 the materials tumble into the ftream, are carried down, and depofited 

 in different parts of its channel ; if large, and heavy, they foon fettle j 

 if fmall, or foluble, they are carried farther. 



. The breach formed on the fide of the valley, mufl neceflarily be 

 fteep, as it is occaConed by the falling down of the materials, which 

 have loft the bafe that fupported them, and which would fupport them- 

 felves on a moderate declivity ; it fliould alfo be reftilineal, uulefs 

 where the valley and river correfpond in fimilar curves. 



Upon the whole, the portion carried away by the river, muft bear 

 the appearance of having been cut off by a plane, whofe inclination 

 does not deviate very far from the perpendicular, 



It is not from our ftudies fuch queftions ihould be difcufled, we 

 fhould refer to Dr. Hutton's code, the book of nature, and examine the 

 fafts upon the fpot, before we deduce fuch general and theoretical 

 conclufions, as he and his friend have done ; 1 fay comlujion, (rather 

 than ajferiton) out of compliment to Dr. Hutton, who is perpetually 

 calling his diiTufe talk demotijiraiion ; it would be uncivil therefore, to 

 call by any other name than conclufion, what he fays, follows from it. 



From the time that I was told that our rivers were carrying away the 

 world, I have paid particular attention to them, whenever I had an 

 opportunity ; and I never met with a fpot on their banks, where it 

 could not be determined, on fimple infpeftion, whether the fides of the 

 valley wer original, or formed ty the depredations of the river j in 



the 



