On the Formation of Valleys. 453 



most easy and direct communication with the stream into 

 which it falls: and all these ranges of valleys are as sub- 

 servient to, and as intimately connected with,. the exten- 

 sive and general system of drainage of the country, as the 

 streams themselves ; and the uniform direction, general con- 

 nection, and admirable subserviency of the whole, are so 

 palpable, that we are irresistibly led to one of two conclu- 

 sions,— either that the several ranges of valleys have been 

 purposely and specially formed for the streams which now 

 flow through them, or that the streams themselves have 

 scooped out their own peculiar valleys. The former opinion 

 is too absurd to merit a moment's attention ; and the latter 

 has so many direct and positive proofs in its favour, as to 

 yield the most satisfactory conviction to any impartial and 

 competent mind, that will take an actual survey of the 

 spring heads and courses of even the most trivial brooks. 



But though there are no natural operations whatever, that 

 from personal inspection more clearly illustrate themselves 

 than this operation of streams in forming their own valleys, 

 it is a subject of considerable difficulty when limited to mere 

 description. The proof circumstances, in all their com- 

 binations, are distinct objects of visual inspection, and when 

 spread out beneath the eye exhibit a connected chain of il- 

 lustrative evidence irresistibly convincing; but the same im- 

 pressive picture is comparatively faint, and its beautiful unity 

 broken into fragments, like the landscape i-n the rippling 

 stream, when held up to the " mind's eye" in the closet. 

 Nevertheless there is a bold prominency in the outline of 

 this natural scenery, which even the pen can trace, and I 

 will endeavour to delineate it in a brief and hasty sketch. 



The horizontal parallelism of the upper brows of vallevs, 

 and of the strata and their identity in the opposite banks, 

 have long ago demonstrated that the strata were formerly 

 continued across, and that the valleys have been formed by 

 the strata being cut through and the missing portions carried 

 away. The truth of this no one will question, who, by ac- 

 tual inspection, has given due attention to the facts upon 

 which it rests. 



The source of every stream is always situated on a higher 

 ¥ t* 3 level 



