494 J. G. Goodchild — On the Origin of Counts. 



tance, Mr. Ward has lately pointed out before the Geological Society 

 that in some of the Cumberland Lake Basins the lines of greatest 

 depth are deflected in the same manner off the mouth of a great 

 branch valley to such an extent that they run well in towards 

 the shore of the lake opposite the mouth of the tributary. Turning 

 to the facts obtained from a study of the behaviour of the Swiss 

 glaciers, we find that where two glaciers unite at a considerable 

 angle, the surface moraines of the more powerfully flowing glacier 

 are impelled right across the path of the smaller glacier, in a few 

 instances nearly to the opposite bank. Besides this, where the 

 valley that a glacier flows in has many bends, the line of swiftest 

 motion crosses the centre line of the glacier at each point of con- 

 trary flexure, exactly as the line of swiftest flow of a river does 

 under similar circumstances. 



Taking these facts into consideration, it will be seen that, inde- 

 pendently of any theory whatever, we can feel a tolerable amount- 

 of certainty that force can be transmitted horizontally for consider- 

 able distances through ice; and the facts obtained from the glaciated 

 surfaces seem to prove that force can be transmitted a considerable 

 distance through ice, not only in a horizontal direction, but also 

 to some extent in a direction approaching the vertical. It seems 

 otherwise impossible to explain the occurrence of the phenomena 

 referred to above except on a supposition of this kind. Those who 

 accept Mr. Croll's theory of glacier motion will at once perceive 

 that these results are precisely such as might have been expected. 



In regard to the quantity of rock removed in this way by the ice 

 from the bottoms of the valleys, we have as yet no trustworthy 

 evidence ; but there is every reason for believing that the quantity 

 of rock ground away from the lower parts of the valley's sides was 

 something considerable, hence it may be safely inferred that the 

 valleys were also deepened in the same proportion. To repeat what 

 was stated above — the ice certainly removed all traces of the pre- 

 glacially weathered part of the rock from the lower ground, and in 

 doing so, while in the main it followed the configuration of the 

 surface left by subaerial agencies in pre-glacial times, it carved the 

 rock surface into forms different in many respects from those re- 

 sulting from subaerial action alone, and bearing characteristics such 

 as can be impressed by the agency only of land ice in motion. 



If, then, there is no alternative but to refer the origin of the 

 straight lines of scar in the Yorkshire Dale District to glacial erosion, 

 it seems to follow that all the accompanying forms of the surface 

 that they are associated with, and that they pass into by insensible 

 gradations of form, must have originated in the same manner. If 

 the slightly concave surfaces of the valley sides are due to the slow 

 grinding of the stone-shod ice-sheet moving horizontally in a slightly 

 curvilinear direction through long periods of time, the more deeply 

 concave recesses that they graduated into, and that occur with them, 

 have assuredly originated in the same way. The only difference in 

 the two extreme cases would be, that in the case of the shallower 

 coum local circumstances did not tend to deflect the ice much out of 



