THE FORMER EXTENSION OF GLACIERS. 
159 
Rhone, where it attains an elevation of over 1350 
metres, or 977 above the lake, descending gradually 
to the plain on one side at Soleure, on the other at 
Gex. At Neuchatel, the erratic blocks form a band 
about 800 feet above the lake. Above and below 
that line they rapidly diminish in number. 
The Rhone glacier then, at the period of its 
greatest extension,* not only occupied the whole 
Valais and the Lake of Geneva, but rising on the 
Jura to a height of 1350 metres, crossed the Vuache, 
descended into the present Rhone valley, sweeping 
round by Bourg, Trevoux, Lyons, and Vienne on one 
side, sent a wing beyond Pontarlier as far as Salins 
and Ornans, and extended down the valley of the 
Aar as far as Waldshut, almost meeting the western 
extremity of the glacier of the Rhine. 
The ancient glacier of the Rhine occupied the 
Lake of Walen, the whole valley of the Thur as far 
as Schaffhausen, the Klettgau, and almost to Walds- 
hut, filled up the Lake of Constance, extending con- 
siderably to the north down the Danube as far as 
Sigmaringen, while for some distance its northern end 
followed the present watershed between the regions of 
the Rhine and the Danube. 
Thus the two great glaciers of the Rhone and 
* See Favre, Carte des Anciens Glaciers de la Suisse. 
