Ancient Extent of the Glaciers of Chamonix. 81 



humble Mount Sion was, as is said by M. Arnold Guyot, to 

 whom we owe this beautiful discovery, the point of conver- 

 gence for these powerful glaciers which have so essentially 

 modified the surface of the plain comprised between the 

 Alps and the Jura. We shall not follow them in all their 

 windings, for all of them present us with particulars analo- 

 gous to those of the glacier of the Arve. Let us merely 

 trace the great features of the limits of the ancient extension 

 of these glaciers. 



The glacier of the Rhone had its origin in all the lateral 

 valleys which intersect the two parallel chains of the Valais, 

 where the most elevated mountains in Switzerland are found, 

 Mont Rosa, Mont Cervin, the Jungfrau, Velan, &c. This 

 glacier filled the Valais, and spread itself in the plain com- 

 prised between the Alps and the Jura, from Fort FEcluse as 

 far as the environs of Aarau. It was the principal glacier 

 of Switzerland ; it is it which has conveyed the innumerable 

 blocks which cover the Jura to a height of 1040 metres above 

 the sea. The other glaciers were only feeble affluents of the 

 glacier of the Rhone, incapable of making it deviate from its 

 direction. Thus, when the glacier of the Arve met it on the 

 ridge of the Saleves or on the sides of the Yoirons, we per- 

 ceive, by the disposition of the moraines, that the glacier of 

 the Rhone continued its progress, while that of the Arve 

 was suddenly arrested. In like manner, a rapid river repels 

 the feeble rivulet which brings the tribute of its waters. 



Other secondary glaciers occupied the principal valleys of 

 Switzerland. Such were the glacier of the Aar, whose last 

 moraines crown the hills in the neighbourhood of Berne; 

 that of the Reuss, which has cov-ered the shores of the Lake 

 of the Four Cantons with blocks severed from the peaks of St 

 Gothard. That of De la Linth stops at the extremity of the 

 Lake of Zurich, and the town is built upon its terminal mo- 

 raine. Finally, that of the Rhine, less studied than the 

 others, occupied all the basin of the Lake of Constance, and 

 extended to the adjacent parts of Germany. 



It appears, therefore, that during the period of cold which 

 preceded the appearance of man upon the earth, Switzerland 

 was a vast sea of ice, one of whose roots were buried in 



VOL. XLIII. NO. LXXXV. — JULY 1847. P 



