24 TRACES OF I HE GREAT ICE AGE IN DERP.YSHIRE. 



of glaciers that we expect to find them. There has been 

 much misapprehension through gauging glacial action from the 

 phenomena to be observed at the terminations of glaciers : 

 here the erosive action is at a minimum. It is high up among 

 the mountain valleys where the glaciers were thickest that 

 we may expect to find the action most strongly marked, and 

 this is exactly where we do find the polishing and grooving 

 already described. But though glacial strice are absent, we have 

 abundant patches of drift, containing in many places ice- 

 scratched boulders. It is interesting to note that in North Derby- 

 shire these deposits are confined to the valley of the Wye, 

 or to that part of the valley of the Derwent which lies below the 

 junction of the two rivers. Above Rowsley, the Derwent valley 

 is free from drift. The explanation of this would seem to be 

 that the drift came from the west, through a gap in the Pennine 

 Chain. The glaciers from the Lake District — prevented from 

 going into the Irish Sea by the enormous mass of ice which 

 filled it — were deflected eastwards, and a portion at least of the ice 

 was driven up the valley of the Mersey, up the Goyt and over 

 the low ridge along which runs the London and North-Western 

 Railway (here not more than i,ioo feet above sea-level), and 

 so into the Wye valley. 



A depression of from i,ioo to i,2co feet would convert this 

 pass into a strait, while it would leave the greater part of the 

 adjoining table-land above water. P'rom phenomena presented 

 by certain shell-bearing gravels near Macclesfield, on Moel 

 Tryfaen, and at Gloppa, near Oswestry, it was held that at some 

 time during the (ilacial Epoch this part of the country was 

 submerged to a depth of at least 1,200 feet, and that the 

 drift deposits of the Wye valley were carried thither by floating 

 ice. It cannot, however, be admitted that the evidence for such 

 a submergence is satisfactory. It has been successfully analysed 

 and disposed of by Mr. Percy F. Kendall. ■■'- Professor James 

 Geikie, who maintained the " great submergence " view, has 



* J'ide " Man and the Glacial Period," G. F. Wright, p. 167. 



