62 A Reply to Mr, Can's Letter y ly Mr. John Farey. 



which the vales are excavated ; oF which the numerous and 

 highly curious deep dry vales, branching from the Dove and 

 Wye rivers in Derbyshire, are well known examples. 



It is by no means a general truth, that if the matters ex- 

 cavated from the strata to fbrm valleys were replaced (page 

 454), " there would still be a sufficient fall in the country 

 for the streams to flow the same tvay." the instances are 

 very numerous to the contrary. If, for instance, Mr. C. 

 will take the trouble, to inspect the course of the Goyte ri- 

 vers on the S.W. of New-Mills in Glossop, of the Derwent 

 river on the S.W. of Matlock church, and many others, he 

 will be forced also to admit, that excavated vales do not al- 

 uays follow the lowest ground. 



It is neither true, that " in every instance the angle of in- 

 tersection of valleys and streams is acute above and obtuse 

 below }" nor that " two streams invariably meet on pre- 

 cisely the same level :" the exceptions are numerous to both 

 of these positions, unless indeed, some quibble or play upon 

 the words be intended therein. 



Since, sir, Mr. Carr and myself are at issue, upon so 

 many of theycr^^ respecting valleys, particularly that, where 

 he says (page 45 7) " a proper examination of the soil be- 

 low every valley will discover the very materials formerly 

 brought down when the valley was excavating," it might 

 appear as invidious as it is at present unnecessary, for me 

 to enter into any examination of the defective reasonings, 

 as I conceive them tu be on some of the assumptions made 

 by Mr. C. 



I must, however, before I conclude, express my surprise, 

 that a person who thought himself justified, in a competent 

 knowledge of the facts respecting valleys, to write thus con- 

 fidently, should have forgot, and not once have mentioned 

 the faults or fissures, so universally met with in the strata, 

 effecting their entire separation into fragments, and causing 

 those great disarrangements of the several pieces or piles of 

 strata, both as to their elevations and inclinations, which are 

 commonly seen, since, the forms of valleys* as well as hills, 

 and of the surface in general, so eminently depend on them 

 ill most instances, but not perhaps in all. 



The 



