Vol. 60.] LAKE-BASINS BETWEEN THE JURA AND THE ALPS. 69 



origin, although there was a prima-facie presumption of these, too, 

 being the result of a lowering of their former river-floors by flexures. 

 In reply to Mr. Hill, he said that there were channels of consider- 

 able length and depth at the upper ends of the Lakes of Constance 

 and Geneva. With regard to Dr. Evans's remarks, the lakes being 

 formed during the retreat of the ice, it followed that the glaciers 

 were probably still melting in the basins as these were forming 

 by a lowering of the floors. In reply to Dr. Jack, he said that 

 the only lateral torrent to which the deep-level Limmat gravel-beds 

 could be due (if not to the main river) was the river Sihl, the alluvium 

 of which was, however, entirely post-Glacial and superficial. He by 

 no means denied the possibility of a former, greater extension, 

 and, consequently, of higher levels of the lakes ; but averred that 

 direct evidence was necessary to prove it in individual cases, for 

 an alluvial plain might also be formed by a meandering river. In 

 answer to Mr. "Whitaker's question, he said that the only fluviatile 

 deposits of the Glacial Period in which, to his (the Author's) 

 knowledge, fossils had been found, were those of the Upper 

 Pliocene Deckenschotter, or alluvion ancienne, near Lyons; 

 while the younger inter-Glacial gravel-alluvia contained few, if any ; 

 but that he had reason to believe that confirmatory evidence — if 

 such were wanted — of the age of the deep-level Limmat gravel- 

 beds (second inter-Glacial period) near Zurich would be found in a 

 similar sequence of deposits in the Rhone Valley near Geneva, with 

 which he proposed to deal on a future occasion. 



