318 THE AGE OF THE LAKE OF GENET A. [Aug. I904, 



one continuous, previously-eroded river-valley ; whereas the Lake 

 of Lucerne lies in two transverse valleys composed of four different 

 troughs, and therefore exhibits, not unlike the Lake of Lugano, a 

 far more complicated structure than other lake-basins within the 

 same zone. The Author fully agrees with Prof. Bonney that the 

 bulk of the low-level gravel-beds underlying the post-Glacial and 

 Glacial alluvia near and below Geneva is derived from the drainage- 

 area of the Rhone Valley : apart from the pebbles of crystalline 

 and sedimentary rocks, as well as of Xagelfluh, of that watershed, 

 this is evidenced more especially by the striking abundance of 

 the Valais gabbro and serpentine (from the Bagne and Saas Valleys), 

 as well as of the green (Tavayanaz) sandstone of Diablerets ; that is, 

 of material transported and deposited, not by the Arve, but by the 

 Ehone.— May 21st, 190Jf^ 



