542 J. E. Marr — Physiography of Lakeland.. 



though at first sight the difficulty of getting a sheet of water other 

 than the sea at a point now forming the watershed between two 

 valleys appears great. Furthermore, the distribution of the super- 

 ficial deposits leads one to infer that if they were entirely removed, 

 we should find the Mosedale Valley practically continuous with 

 that of Wet Sleddale. How, then, is the nature of this col to be 

 accounted for ? 



Its extreme flatness forbids the idea that it is a dry delta 

 brought down during violent floods by the Little Mosedale 

 stream (L.M. Fig. 2), which seems the easiest explanation. 

 Moreover, the material beneath the peat is not of the character 

 which we should expect on this supposition. The mixture of stones 

 and very fine clay suggests deposit in still water, combined with 

 the agency of ice, but the occurrence of a tract of still water in a 

 position now occupied by a col between two valleys necessitates 

 the existence of two barriers, one between Mosedale and Swindale 

 proper, the other in Wet Sleddale below the peat-covered slope. If 

 the Mosedale Valley were, as it appears to have been, at one time 

 a continuation of Wet Sleddale, an ordinary barrier of rock (possibly 

 somewhat rotten, as is often the case on the ridges of this district) 

 would intervene between it and Swindale, but no such barrier can 

 have existed lower down Wet Sleddale, and the only possible barrier 

 in this direction which would produce the required effects is one of 

 ice. A mass of ice crossing the Wet Sleddale Valley in its lower 

 part would pond back the waters of the upper part of the valley 

 (including what is now Mosedale) and convert it into a lake. The 

 water of this lake would escape over the lowest point, which was 

 probably situated in Mosedale a little below the present col between 

 it and Wet Sleddale; this col must have been more than 1540 feet 

 high (the height of the flat-topped col), and must have been less than 

 1661 feet (the height of that between Mosedale and Long Sleddale). 

 The water thus switched off into Swindale would cut out the 

 portion of the valley now running north and south between the 

 alluvial col and the Forces. As the stream, at the point where 

 the ridge between Mosedale and Swindale is supposed to have 

 existed, is about 1300 feet high, an erosion of less than 200 feet 

 is required, which could be readily performed during the period 

 which has elapsed since the existence of the ice- dam. Granting the 

 formation of this ice-dammed lake, we have all the requisites for 

 the formation of the flat-topped watershed of superficial detritus. 

 The fine clay would be derived from melting icebergs, as would 

 also some of the stones with which it is mixed, whilst others would 

 be brought into the lake by the Little Mosedale stream to form a 

 subaqueous delta, which would eventually extend right across the 

 lake and cut it in two, thus entirely separating what is now Mosedale 

 from Wet Sleddale, and diverting its waters into Swindale. If the 

 large volume of water which now runs over the Forces has been 

 thus diverted in that direction, comparatively recently, this will 

 account for the insignificant groove which those waters have cut 

 out, whereas, if Mosedale had always been part of Swindale, it 



