44 Old Glaciers of Switzerland. 



among mountains of the second and third classes, as if 

 they were not sufficiently lofty to have contributed 

 their quota of ice to fill the minor valleys. But on the 

 map that accompanies Professor Rutimeyer's memoir 

 on the Pliocene and Glacial epoch, that distinguished 

 author has boldly drawn a continuous line of moraine- 

 matter, extending from Lyons along the south-east flank 

 of the Jura, and from thence to Steyer, in Austria, about 

 20 miles from Linz on the Danube. 



I do not doubt the general fidelity of this bold gene- 

 ralisation, and if it be true, it seems to me that, during 

 the most intense part of the Glacial epoch, the whole of 

 Switzerland between the Alps and the Jura must have 

 been covered with glacier-ice. If so, to the eye (had 

 human eyes been there to see it) it must have been im- 

 possible to specialise individual glaciers such as those of 

 the Rhone, the Rhine, the Linth, the Reuss, and the 

 Aar. Nevertheless when we consider the great an- 

 tiquity of the post-Miocene disturbance of the Alps, 

 I do not doubt that in some form those valleys 

 existed, in which case the great glacier, maintaining an 

 average uniformity of surface, must still have been 

 thickest in the lines of the pre-existing valleys, and 

 the erosive power of the moving ice must have been 

 proportionally increased thereby. The effects produced 

 on the country over which the under-current of the 

 Rhone glacier flowed were commensurate to its great 

 size and thickness. 



The Lake of Greneva where deepest, towards its eastern 

 end, is a little more than 1,000 feet in depth, and it 

 gradually shallows to its outflow. By examining the 

 sides of the mountains on either side of the valley of 

 the Rhone, through which the glacier flowed, we are 

 able to ascertain what was the thickness of the ice in 



