Vol. 68.] GLACIATION OF THE BLICK COMBE DISTRICT. 



427 



5^ 



Were it not for the transverse valleys at Gill foot and Corrney 

 Hall, there would be nothing inconsistent in the view that the 

 parallel sequence of channels — Kinmont, 

 r-^W;009r^ Corney, and Xear Bank — was formed during 



a retreating movement of the ice, after it 

 had advanced over the gravels which it had 

 previously deposited, because the heads of 

 the three longitudinal channels are so re- 

 lated to the contours that each would have 

 come into operation after the next above 

 it had been abandoned. The transverse 

 valleys, however, seem to show that different 

 parts of the longitudinal channels were cut 

 at different times. 



Assuming first that the ice, after an 

 advance over the gravels, was retreating, 

 and that the Kinmont Channel was cut, the 

 formation of the Gillfoot cross-cut would 

 require a small retreat of the ice, and a 

 filling up of the lower part of the Kinmont 

 Channel, so that the water would be com- 

 pelled to flow over a low col, or along a 

 pre-Glacial hollow, on the site of the Gill- 

 foot Channel ; and then, following the ice- 

 margin, commence to cut that part of the 

 Corney Channel which is south of Gillfoot. 

 This result might conceivablj' be brought 

 about by snow filling the lower part of the 

 Kinmont Channel — local glaciation being 

 out of the question. Further retreat of the 

 ice-margin would cause the water to abandon 

 the upper part of the Kinmont Channel and 

 open up the whole length of the Corney 

 Channel, which would be cut almost to its 

 present low level. The formation of the 

 Corney-Hall Channel may have been due 

 to a similar process, the col at the Hall 

 being formed by an oscillatory movement 

 which threw the waters back for a short 

 time from the Near-Bank Channel into the 

 Corney Channel. 



There is, however, a second possible ex- 

 planation, namely, that the parallel sequence 

 was cut during the forward movement of 

 the ice when it overrode the gravels. It 

 has been recently demonstrated^ that a slight 

 advance of a glacier is often followed by 



^ O. D. von Eugelii, 'Phenomena associated with Glacier-Drainage & 

 Wastage ' Zeitschr. fiir Gletscherkunde, vol. vi (1911) pp. 128, 129. 



