EXPLANATION OF MAP OF THE ANCIENT RHONE 

 GLACIER. 



Outline map of part of France and Switzerland, showing the course 

 of the ancient Rhone glacier at the period of its greatest extension, 

 to illustrate the account here given of the dispersal of Alpine erratics, 

 as well as of the erosion of the basin of the Lake of Geneva by the 

 glacier. 



Explanation. 



1. The parallel and diverging blue lines show the courses of the 

 various streams of erratics carried by the glacier. 



2. The arrows at end of these lines show the positions of the most 

 distant Alpine erratics, or of drift containing fragments of Alpine 

 rocks. 



3. The Blue figures show the height in feet of the ice-surface above 

 sea-level, as shown by ice- worn rocks or erratics in the'vicinitj'. The 

 actual elevation of the ice was perhaps much greater. 



4. The Black figures show the heights of land or water surfaces above 

 sea-level. 



5. The tributary glaciers (except that of the Arve) are omitted for 

 clearness ; bvit the whole area between the Alps and the Jura, except 

 a few high summits, was buried in ice. 



N.B. The lines showing the course of the erratics are taken from 

 A. Falsan's large map published in 1887. 



