286 SUMMER. 



a lake many miles in surface, and had a depth of at 

 least three hundred feet. The strata are by no means 

 soft, and yet the force of the water has been such, that 

 the whole is cleared away to a continuous rocky chan- 

 nel during the whole extent. In the south of Forfar- 

 shire there is one still more remarkable, as not only 

 the principal rivulet, but some of the lateral ones that 

 are dry in the summer, have performed the same ope- 

 ration. The principal stream is a very small one, and 

 not sufficient on ordinary occasions for turning a com- 

 mon corn mill, without the water being accumulated in 

 a pond. The Dee, opposite to the grounds of Wynn- 

 stay, in Denbighshire, shows a very remarkable one 

 when the water has made a circuit of about a mile, to 

 avoid cutting not exceeding 200 or 300 feet of harder 

 substance; and above Llangollen, there are some other 

 remarkable instances. Every mountainous part of the 

 country, indeed, exhibits many instances of the pro- 

 cess ; and it is worthy of notice, that the fragments of 

 stone in the gravelly soil of those basins of old lakes, 

 and even in the beds of the streams that flow through 

 them, are much more angular, and have, of course, 

 been much less rolled about and rounded by the water, 

 than those where there have been no such occurrences. 

 From that, we may infer that the general action by 

 which the fragments of stone in the gravel of other 

 places were rounded, happened before those places 

 were emptied ; and that therefore, the whole of the 

 emptying has been brought about by the gradual 

 action of the water, subsequent to any thing like a 

 general commotion. This makes each of those places 



