546 Miss Eyton — On Glacio- Marine Denudation. 



they have been largely denuded by glacial and marine agency ; so 

 that, if we are indebted to the god Pluto for having opened to us 

 his stores of subterranean wealth, his brother deity, Neptune, may 

 claim a share of our gratitude for having, by more gentle means, re- 

 moved some of the obstacles to its acquisition. 



The western boundary of the basin is formed by the basaltic 

 ridge of Haughmond Hill, which, with its opposite neighbour, the 

 Wrekin, form the barriers on either side of the outlet. After this 

 ridge is passed the basin widens considerably, and the outline is, in 

 places, broken. It is, however, perfectly distinct in the Sandstone 

 Hills of Grinshill, and in the neighbourhood of Hawkestone. 



In the lowest part of the area there lies an old lake basin, some 

 seven miles in length, by four in width, now called the Wealdmoors,^ 

 and it is upon the evidence of this basin that the glacial theory 

 principally depends. I am at a loss to conceive any other denuding 

 agent than ice, with sufficient force to act upon so large an extent of 

 surface in a circular direction. It must be remembered that the 

 Wealdmoors certainly existed as a lake at the period of the Low- 

 level drifts, and, consequently, that the excavation must have been 

 effected previously to that period ; that is to say, either during the 

 period of marine submergence, or before it. Now the action of the 

 sea is always in straight lines : it may form cliffs, terraces, or lines 

 of shingle, but it is incapable of working in a circular direction, save 

 in the exceptional case of a whirlpool, or a concentration of local 

 currents, flowing from various directions ; and to produce either of 

 these, there must be some local cause, as sunken rocks, of which 

 there is no trace in this instance. I infer, therefore, that the de- 

 pression in question was produced by a mass of frozen matter, which, 

 being heaviest in the centre, was continually pressing the lower 

 fragments outwards, and from which small streams of water were 

 continually flowing at the lowest point of contact with the earth. 

 If, as Mr. E. Hull has demonstrated,^ a valley within a valley is a 

 proof that the outer one is of marine origin, I think a basin within a 

 basin may be taken to show the same with regard to ice. The 

 Wrekin must certainly have once formed an ice-shed. Between the 

 Ercall and Lawrence's Hill, in the Wrekin chain, there occurs a deep 

 rift, now occupied by a small mountain stream, but when we con- 

 sider the hardness of the rock through which the channel is cut, it 

 seems scarcely possible that such a rivulet could have effected it. 

 Besides, the chasm is stre'^\Ti with large masses of rock, firmly fixed 

 in the mud and gravel, brought down annually by the stream, and 

 overgrown with vegetation; evidently the remains of a far older 

 drift. Other ice-rifts occur in this chain of hills. On the face of 

 Haughmond Hill, towards the Severn, are four or five distinct 

 furrows, or grooves, apparently ploughed into the hill by masses of 

 frozen matter precipitating themselves into the valley below. 



I have not yet succeeded in finding any beds of ascertained glacial 

 drift in the basin itself, but there are traces of its existence in the 



' See Geological Magazine for January, 1867, for a detailed account. 

 ' Modern views of denudation. Popular Science Review, Oct., 1866. 



