1 80 The Founders of Geology LECT. 



was beautifully expressed by Playfair : " Every river 

 appears to consist of a main trunk, fed from a variety of 

 branches, each running in a valley proportioned to its 

 size, and all of them together forming a system of valleys, 

 communicating with one another, and having such a nice 

 adjustment of their declivities, that none of them join the 

 principal valley, either on too high or too low a level, a 

 circumstance which would be infinitely improbable if each 

 of these valleys were not the work of the stream that 

 flows in it. 



" If, indeed, a river consisted of a single stream without 

 branches, running in a straight valley, it might be supposed 

 that some great concussion, or some powerful torrent, had 

 opened at once the channel by which its waters are con- 

 ducted to the ocean ; but, when the usual form of a river 

 is considered, the trunk divided into many branches, 

 which rise at a great distance from one another, and these 

 again subdivided into an infinity of smaller ramifications, 

 it becomes strongly impressed upon the mind that all 

 these channels have been cut by the waters themselves ; 

 that they have been slowly dug out by the washing and 

 erosion of the land ; and that it is by the repeated touches 

 of the same instrument that this curious assemblage of 

 lines has been engraved so deeply on the surface of the 

 globe." 1 



The whole of the modern doctrine of earth-sculpture 

 is to be found in the Huttonian theory. We shall 

 better appreciate the sagacity and prescience of Hutton 

 and Playfair, if we remember that their views on this 

 subject were in their lifetime, and for many years after- 



1 Illustrations of the Huttonian Theory, p. 102. 



