Charpen tier's Efisay on the Glariertt. 117 



enlarges, the glacier must necessarily have become lower, and, 

 in fact, the debris rise only to 2500 feet above the Rhone. This 

 height has continued for an extent of 17 leagues, as far as 

 Martigny, the width of the valley remaining nearly the same. 

 It becomes narrower from Martigny to St Maurice, and the 

 debris rise to nearly 3000 feet, then fall to 2300 feet till we 

 come to the lake of Geneva, the glacier having necessarily be- 

 come lower owing to the great enlargement of the valley of the 

 Rhone. Having reached the basin of the lake, the glacier was 

 freely extended to the west and in the direction of Thonon. its 

 lateral edge sinking to the level of the lake. To the east, on 

 the contrary, the plateau of Jorat forced it to rise to 2600 feet, 

 an elevation indicated by the debris deposited on the mountain 

 of Playau. After passing the Jorat, the diluvial glacier of the 

 Rhone arrived at the Jura. There the insurmountable obstacle 

 presented by that chain of mountains put a stop to its progres- 

 sive movement ; the glacier rose upwards, and deposited its 

 frontal moraine at 3000 feet above the lake of Neuchatel ; while 

 on the two sides, encountering no obstacle, it became enlarged 

 by diminishing the thickness, and described, on the sides of 

 the Jura, the curve now presented by the debris of the erratic 

 formation, which terminate on the one side near Soleure, and 

 on the other near Gex. 



The manner in which the erratic formation terminates, 

 sometimes in the form of mounds or bands analogous to mo- 

 raines, sometimes in scattered debris, or by mingling gradually 

 with the diluvmm, which must have been necessarily conveyed 

 by the action of the mighty torrents which escaped from the 

 sides of the diluvial glaciers ; at other times, finally, becoming 

 confounded in a way which cannot be disputed, with the de- 

 bris and moraines of existing glaciers, — are all facts which 

 seem to plead powerfully in favour of the hypothesis of glaciers. 



With regard to the considerable extent which the erratic 

 formation of the valley of the Rhone seems to present, it is 

 easy to understand why the glacier furnished by this valley 

 should have been so infinitely larger than any of those which 

 have reached the plain at the bottom of the Alps. In fact the 

 Valais, for four-fifths of its length, is bounded by two of the 

 highest chains of the Alps, and receives the greatest number 



