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LXXXl. On the Natural Causes which operate in the Forma- 

 tion of Valleys. By John Carr, Esq, 



**■ Revolving the circumstances of excavated valleys in my mind, as I have 

 observed them wonderfully distributed over the whole surface of large di- 

 stricts, effecting a descending outlet or drainage to any part : I have been lost 

 in conjecturing any application of mechanical or known principles, that 

 could have directed the almost irresistible forces, which effected this impor- 

 tant, and as k were finishing operation on the matter of our globe, but refer 

 the same to Omnipotent Power itself, acting, perhaps, in this instance, with- 

 out the intervention of the agents whose operations in Nature the light of 

 science enables us in so many instances to trace." 



Mr. John Farey, Philosophical Magazine for April 1809. 



To Mr. Tilloch, — Sir, 



jL he above M most lame and impotent conclusion" fur- 

 nishes a very singular instance of the great difference between 

 observing and judging ; between the accurate perception of 

 effects, and the more rare and discriminating faculty of 

 drawing from their common agreement and general com- 

 bination, just and rational deductions of their cause. Phe- 

 nomena so extensive, combined in such union, and ope- 

 rating so indispensable an office in the wise ceconomy of 

 Nature, surely ought to have suggested a more natural and 

 philosophical inference. To me, there are few things more 

 evident than that " the irresistible forces" which have effect- 

 ed the excavation of valleys, are no other than the identical" 

 streams which now flow through them ; and that by means 

 go natural and obvious, as to excite extreme wonder how so 

 experienced and intelligent an observer, as Mr. Farey un- 

 questionably is, can have surveyed the practical facts, and 

 reflected on the subject, without arriving at the clearest 

 conviction. 



Every river which disembogues itself into the ocean is 

 the great drainage trunk of a considerable extent of country, 

 receiving through every part of its course lateral streams, 

 which again receive others, and these others still, in so much 

 that the river itself is frequently the receptacle of hundreds 

 of other streams of various magnitude and extent ; and not 

 only the river, but every brook, however remotely con- 

 nected, has its peculiar range of valleys, which afford it the 



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