VOL. XVII. (I) SOME GLACIAL FEATURES IN WALES 41 



down in the vale there are extensive deposits of roughly-worn 

 limestone and ironstone-fragments from the Lias and Oolites 

 of the escarpment ; quartzose sand, with a varying amount of 

 well-rolled, and somewhat stratified gravel (made up of frag- 

 ments also from the Oolite and Lias) ; and the so-called 

 " Northern Drift," which comprises quartzite pebbles (obviously 

 from the Bunter), pieces of flint, chert, etc. 



The present distribution of these several types of Super- 

 ficial Deposits — sometimes capping the undulations in the vale, 

 and at others filling up inequalities in its surface, while clear- 

 swept valleys often exist between — points emphatically to the 

 conclusion that, previous to their distribution, while the 

 main land-features were not widely different from what they 

 are to-day, the actual surface of the vale-land was somewhat 

 differently sculptured, and that while deepish valleys now 

 lie buried beneath thick deposits of quartzose sand, valleys 

 exist where once spread clay. 



What precisely were the conditions that obtained in the 

 Lower Severn Valley and the Cotteswold Hills during Glacial 

 times is doubtful, and for the present purpose does not matter 

 much, for certain points are obvious. One is that previous to 

 the introduction of the foreign constituents of the Superficial 

 Deposits af the Lower Severn Valley — and it will be sufficiently 

 accurate to say, in pre-Glacial times — the actual surface of the 

 vale was of somewhat different land-relief, and it is equally 

 obvious that such was the case also with regard to the upland 

 and its flanks. 



Hence, restricting our attention to the hill-mass now 

 called Leckhampton Hill and Charlton Common, it may be 

 suggested that, in pre-Glacial times, it was a portion of a 

 normally subdued escarpment, incised by the growing obse- 

 quents of the River Severn, whose numerous branching heads 

 sprang from the valleys between rounded spurs on the hill- 

 sides, and flowed Severnwards down well-graded slopes across 

 an undulating vale-land. 



But then came the Glacial Epoch. Over the inequalities 

 of the vale were strewn the deposits of sand derived from 

 further north, and snow collected on the hills, and especially 

 in the many-branching stream- valley-heads in the hill-sides. 



