314 [Proc. B.N.F.C., 



posited from the melting of the ice at the end of the glacier, 

 forming terminal moraines. It was formerly thought that ice was 

 capable of yielding to strain, from the action of the glacier in 

 accommodating itself to the valleys through which it passes, but 

 experiment fails to detect this property of ice. It would appear 

 rather that it is the property of ice in uniting its parts after 

 fracture which enables the glacier to do this. The grooves and 

 scratches in the lower parts of the glacier valleys, as well as the 

 evidence of these in districts now entirely void of glaciers, give us 

 some idea of the part taken by these masses in the denudation of 

 past ages. Referring similar results to similar causes, we must 

 conclude that where these effects exist the cause did. It is this 

 cause which in past times rounded our Irish, Scotch, and Welsh 

 hills. We are able to distinguish the stones transported by 

 glaciers trom those carried by rivers from the angularity of the 

 former and the roundness of the latter. It is these marks which 

 form an important part of the alphabet of the geologist. 



The effect of elevations in condensing vapours carried by winds 

 appears to me to be imperfectly explained. It is usually stated 

 that the wind, say, meeting with a mountain range, has its vapour 

 condensed, from which one is to gather that this is brought about 

 by the direct cooling effects of the mountain, as in the case of 

 dew. I think it would be better explained by the wind, having to 

 ascend to greater elevation, is subjected to less pressure, when by its 

 elasticity it expands, does work, loses heat, and has its vapour 

 precipitated. The portion of rain water which is not re-evaporated 

 or absorbed by plants appears again as rivers. These give an 

 example of what water may do in a liquid state. 



Mr. Robinson then explained the chemical action of river 

 water, and the important work effected by this means, especially 

 on limestone rocks. He also referred in detail to the mechanical 

 action of rivers and of the ocean in promoting the work of 

 denudation, the aqueous agency being seen to be opposed 

 to the igneous. 



