150 



that the particles are small and free from common rubble. 

 This is, 1 think, suggestive of the periodical shelling off from 

 the rock surfaces of thin flakes or fragments, which became 

 still further pulverized before they were carried away to be 

 deposited in the Gravel bed. 



It is necessary, therefore, to consider in what other manner 

 these Gravel beds may have been formed. I think it will be 

 found that they are attributable to different conditions, and were 

 deposited at different periods. The Gravel which lies imme- 

 diately below the Freestone beds of the Inferior Oolite, where 

 the slopes are always very steep, is, I think, merely detritus, 

 which, having been previously loosened by frost, periodically 

 fell from the rocks on the warm weather setting in, and which 

 either rolled down the slope or was washed down by surface 

 water. Its position is generally on the slope where the incline 

 becomes less, and exactly where we should expect to find it, 

 assuming that it had come down the hill in the way suggested. 

 But the Gravel which lies in ii-regular positions on the slope, 

 at distances from the Oolite beds from which it has been derived 

 which preclude the possibility of its having at once fallen on its 

 place of deposit, and in positions similar to those shewn in the 

 section at Hyde, is more difficult of explanation. I am of opinion 

 that this is due to storm waters or surface drainage, which 

 brought the detritus down the hill upon a frozen surface, and 

 deposited it in those places where the frost usually disappeared 

 in spring before it left the higher ground. 



If we imagine a period when the severity of winter was 

 much greater than at the present time; when the hills were for 

 the most part bare of vegetation, and the oolitic rocks more 

 exposed, there would be little or nothing to check the waste 

 occasioned by frost and rain. The climate in spring was 

 then probably as changeable as now. The snow that covered 

 the ground in winter would first disappear in the valleys, but 

 would remain on the hills and the upper part of the slopes, 

 and the changes from frost to mild weather, and vice versa, 

 would, from the variable character of the climate, be frequent. 

 As a necessary consequence, the upper part of the slopes 



