the Alpine Lakes and Valleys. 207 



I am a strong partisan of the notion of the transport of 

 erratic blocks by ice, at the period of the great extension of the 

 glaciers, and as a Swiss I am attached to this theory, which is 

 worthy of the term national. But, at the same time that I 

 acknowledge it to be accompanied by certain difficulties, I can- 

 not comprehend the two other theories, although they have the 

 advantage of being advocated by able men of science. Amongst 

 these is to be counted Professor Ramsay, a highly distinguished 

 geologist, to whom long practice on the Geological Survey of Eng- 

 land has given great powers of observation and a sure eye [coup 

 d'osil), Mons. de Mortillet, who is well acquainted with the 

 Alps, and Professor Tyndall, whose works on physics hold the 

 first place. Not that I do not sincerely respect the opinions of 

 the learned authors who have developed these views, and who 

 have done so, I acknowledge, with considerable ability. 



It is evident, indeed, that existing glaciers abrade the rocks on 

 which they move, inasmuch as they polish them. But this action is 

 so feeble, that I cannot see how it has been inferred therefrom 

 that it has been able to scoop out deep lake- basins many hun- 

 dreds of feet below the mean level of the valleys, even on the 

 supposition that it has been exerted during very long periods. 

 I understand still less how this same action could have excavated 

 valleys many thousands of feet deep in a great rock-mass like 

 that of the Alps. 



A limit must be set to certain effects. This limit exists in all 

 geological questions, and it is indispensable to establish it. 



On seeing a dune on the sea-shore, twenty or thirty metres 

 high, formed by means of grains of sand driven by the wind, 

 shall I be right in concluding that in some hundreds of thou- 

 sands of years this same dune could attain the height of the 

 Alps or that of the Himalaya ? 



I have no wish to maintain that the glaciers have not exerted 

 any influence on the forms of lakes and valleys. It seems to 

 me to be impossible that masses so considerable as those which 

 moved in the valleys during the glacial epoch, should not have 

 fashioned, more or less, the borders of these depressions. But 

 I cannot become an advocate of the belief that glaciers are the 

 original cause of the formation of lake-basins and valleys. I 

 believe both to be a direct consequence of the formation of 

 mountains, and that they both owe their origin to movements 

 of the earth's crust. 



Let us now leave these general arguments, and arrive at 

 more precise facts relative to the origin of the Lake of Geneva. 

 According to all glacial theories, the union of all the glaciers of 

 the Valais at Martigny, to a portion of those of the main body 

 (massif) of Mont Blanc, formed one enormous glacier, to which 



