ORIGIN OF THE ROCKS AND SCENERY OF NORTH WALES. 267 



vastly higher than Snowdou itself. But this is not all that an accurate 

 section proves. By completing the curves we can estimate roughly the 

 amount of material removed, and in this way prove that thousands of feet of 

 solid rock have been completely swept away. The only agent with which we 

 are acquainted, capable of performing this work, is moving water, whether 

 in the form of rain, rivers, glaciers, waves, or oceanic currents, and we 

 are, I submit, driven to conclude that this is the agent which has effected 

 the removal. We need have no hesitation in granting the truth of this 

 when we remember that the stratified rocks themselves are evidenoe of 

 the potency of this agent. 



But how has the existing distribution of hill and dale been brought 

 about? A careful examination of any valley, such an one for 

 instance as the Pass of Llanberis, is quite sufficient to convince any 

 unprejudiced person that the rocks on either side were once con- 

 tinuous ; that the valley, in fact, at one time did not exist. It is 

 further sufficient to prove that the formation of the valley was not due to 

 the cracking and opening of the earth's crust, but to the removal of the 

 material formerly occupying the valley ; for the rocks on either side and 

 in the bed of the valley (I am thinking now more especially of that 

 portion of the Pass of Llanberis in the neighbourhood of the old village 

 of Llanberis) bear to each other a relation similar to that which the 

 two sides and bed of a newly-made railway cutting bear to each other. 



"What is the agent which has hollowed out the valley ? I answer 

 again without hesitation, moving water. The stream now flowing down 

 the valley tends in many places to deepen it, and this represents the 

 process by which the valley has been formed. In looking at the enormous 

 size of a valley such as the one we are considering, and comparing this 

 with the power of the existing stream to deepen its bed, we are struck 

 with the utter insignificance of the latter, and we experience a great 

 difficulty in believing that such a cause could produce such an effect. 

 Nevertheless, when we reflect that the amount of denudation represented 

 by the formation of this valley — and indeed all the valleys of North 

 Wales put together — is absolutely insignificant when compared with the 

 denudation which is proved to have taken place by the geological 

 sections, when viewed on the large scale ; and when we reflect further that 

 the stratified rocks, of which the earth's crust is composed, give 

 unmistakeable evidence of having been formed by water action, our 

 difficulty vanishes, and we find ourselves firm in the faith that valleys 

 owe their origin to this agency. 



If we imagine the valleys of North Wales filled up, as they must 

 have been, before the existing streams began their work of denudation, 

 we see that the country instead of being characterised by rugged 

 mountains, jagged ridges, and steep precipices would really be tame and 

 uninteresting. Under this state of things a person might walk without 

 let or hindrance from Moel Hebog to the high land overlooking the sea 

 near Conway, without ever rising far above, or sinking far below, a height 

 of 2,500 feet. To the left of his line of march the country would sink 

 towards the N.W., while on his right it would stretch for many miles at 



