166 ORIGIN OF CUMBERLAND AND WESTMORELAND LAKE-BASINS. 



nated in the difference of hardness of the material eroded hy glaciers. 

 He did not think that basins were necessarily formed only at the 

 terminations of glaciers. The meeting of two rivers produces a 

 great turmoil in the waters, increasing their erosive powers, and 

 producing a pool. This may be the case also with the meeting of 

 two glaciers, although from the nature of the material it is not 

 directly recognizable ; but the pressure and grinding-power would 

 be greatest there. 



The Rev. T. G. Bonney agreed with Mr. Drew that Mr. "Ward's 

 observations, though very valuable, could not necessarily be applied 

 to explain more than the region described. Though he admitted 

 Mr. Ward had established his point, on the whole, for the English 

 lakes, he did not think that the larger Swiss and Italian lakes could 

 be so explained. He had carefully examined both districts : in the 

 former the configuration of the ground was such as generally 

 favoured glacier- erosion ; in the latter the evidence went quite the 

 other way. 



Mr. Koch remarked that one of the most interesting points brought 

 forward by the author was that relating to the comparative thickness 

 of the ice and the depth of the excavations. He thought that care- 

 fully pursued researches in this direction would probably lead to 

 valuable results. 



Mr. Evans thought that there was an inclination on the part of 

 some geologists to undervalue the grinding-power of glaciers ; but 

 the muddy water from the foot of a glacier shows that this power is 

 considerable. When the passage for the ice is contracted, as at the 

 incoming of a glacier from a lateral valley, there must be an increase 

 of the grinding-power. 



Mr. Ward replied to Mr. Drew, that the horizontal or but gently 

 sloping upper surface of the ice, as shown in the sections, was purely 

 diagrammatic ; in nature this surface may in many cases have pre- 

 sented great irregularities. "While believing that many tarns lying- 

 in combs have been excavated by glaciers often generated on the 

 comb-slopes, he maintained that the larger lakes, such as Wast- 

 water, with its greatest depth beneath the sea-level, could not have 

 been formed merely at the end or snout of a glacier, but were due 

 to the passage of a thick glacier-sheet through the valley-length 

 over the present lake-sites. Whether the paper did or did not ad- 

 vance Prof. Eamsay's theory in general, if it had proved the glacial 

 oi igin of the Cumbrian lakes its purpose had been effected. 



