UNCLE IN ENGLAND. 15 



forward ; and the more the water was confined 

 to a channel, the more powerful was its action. 

 But J;he hills have also been disturbed more or 

 less ; for the upper strata appear to have heen 

 swept off from extensive ranges that they once 

 covered. This is proved by the separated hills, 

 which geologists call outliers and which, having 

 the lower strata exactly continuous with those 

 of the adjacent range of mountains, but want- 

 ing the superior strata, shew that the same 

 convulsion which broke through and carried 

 away the connecting parts, must also have torn 

 off their summits: Another proof is the great 

 quantity of their debris, or broken fragments, 

 which are found scattered over parts of the 

 country far distant from their original positions. 

 In the gravel beds near London, I have found 

 pieces of basalt, though that species of rock is 

 not known to exist within a hundred miles of the 

 county of Middlesex. 



" These fragments," he continued, " must, 

 therefore, have been transported by some agent 

 that was equal to tearing up and carrying away 

 the parent rock ; and when it is considered that 

 all gravel must have had its edges and angles 

 rounded by the rubbing of stone against stone, 

 you will perceive that this could only have been 

 effected by the violent and long-continued action 

 of currents of water ; in short, by the tremendous 

 surge and confused motion which accompanied 



C 2 



