J. G. Goodchild — On Glacial Erosion. 357 



Subaerial Denudation. Even where there is no stream to remove the 

 weathered material as fast as it falls, some geologists would probably 

 consider the combined action of springs and the weather quite 

 sufficient to give rise to the features in question. But in the par- 

 ticular district here referred to there seems to be evidence to prove 

 that this view is incorrect. It will perhaps be sufficient to refer to 

 the following points in confirmation of this. Wherever springs are 

 found in such a series of alternations of beds of different lithological 

 character as forms the hills of the Dale District, they usually occur 

 at irregular and often at distant intervals along the bases of the more 

 permeable beds. In most cases, especially in the lower beds, the 

 springs issue at the line of junction of a limestone with the more or 

 less impervious bed that it lies upon. Most of the spring water thus 

 thrown out has usually flowed only a short distance under ground ; 

 in the generality of cases the water that flows over the surface of the 

 usually impervious bed above sinks as soon as it reaches the open 

 joints of the limestone and collects over the next impervious bed 

 beneath, by which it is again thrown out to the day. Thus it follows 

 that, where little water finds its way on to the limestone, as little 

 is thrown out as springs ; but where the limestone is near the edge 

 of a considerable flat, especially if there is also a peat moss near, 

 springs of considerable size make their appearance. The steep slopes 

 of the fell-sides in the dales usually prevent the wide spreading 

 of any great quantity of water, which for the most part finds its way 

 to a lower level without forming many springs in its course ; but 

 high up on the fell-sides, near where the flatter surface begins to be 

 covered with peat mosses, the greater part of the water that comes 

 down the fell-sides issues from the springs that are found along the 

 base of the highest thick bed of limestone. In other words, at low 

 levels there are found but few springs, and those only small : while 

 in the higher parts the springs are both numerous and of compara- 

 tively large volume. When we compare the forms of the scars in 

 the two places, it is at once apparent that where there are but few 

 springs, that is to say, in the low ground, the characteristic sweeping 

 outline and general uniformity of character of the scars, is retained ; 

 while where there are many springs, as in the higher parts, the wide 

 and irregular notches that break the regularity of the scar's outline, 

 and the accumulation of fallen blocks that have been undermined, 

 plainly indicate that the springs are slowly destroying the present 

 regularity and replacing it by a form of surface altogether different. 

 To put this in another form : — where there are no springs we get 

 the most perfect outline and a surface without much fallen rock : 

 where there are many springs the rock features present a broken and 

 irregular outline, and the slopes beneath are encumbered with the 

 rock thus degraded. Again, the springs do not come out at regular 

 or at close intervals, but are confined to certain positions that are 

 usually determined by either the lie of the rocks or the general 

 direction of the streams whence most of the water is derived. To 

 produce anything like the regularity of form that one sees in the 

 scars, the springs must have acted at regular and close intervals all 



