220 M. Charpentier on the Glaciers oftfie Canton Vallais. 



time elevated to a much greater height than they at present 

 possess. So vast an occurrence must have caused displacements, 

 ruptu rings, fractures, and the formation of hollow spaces ; the 

 upraised masses must have fallen together, and sunk until all 

 the unsupported parts again assumed a fixed position, and the 

 whole mass acquired its present stability. 



The elevation to so great a height above the sea, in combina- 

 tion with the diminution of the temperature of the earth itself, 

 must have produced a great change in the climate of these dis- 

 tricts. The climate which was capable of producing the Cha- 

 mcBrops, and other plants of warmer lands, must have been 

 converted into the climate of high northern latitudes. The at- 

 mosphere was cooled ; the Alps were covered with snow, which, 

 as it constantly fell into the valleys, formed those vast glaciers 

 which gradually covered the whole of lower Switzerland, and 

 pushed their moraines to the summit of the Jura. These gla- 

 ciers then began to diminish and to retire, when the sinking al- 

 ready mentioned took place ; and as the height of the Alps, the 

 Jura, and the intermediate flat countries, became gradually less 

 considerable, the climate gradually ^became warmer, until at last 

 it acquired its present temperature. 



The ChamcErops formerly flourished in the neighbourhood of 

 Vevey and Lausanne, That district probably formed, as al- 

 ready mentioned, a coast lowland, and must have had a mean 

 temperature of 17°.5 cent. (64° F.) The mean temperature of 

 those alpine valleys in which glaciers are not indeed formed, 

 but are preserved, is 6° (43° F.) This is, for example, the mean 

 temperature of Chamouny. If we assume that the temperature 

 diminishes 1° cent, for every 160 metres diminution of height, 

 then the land which had a mean temperature of 17°.5 must 

 have been elevated 1840 metres (17.5 — 6x160 = 1840), in 

 order to reduce the temperature to 6°. But as the present height 

 of Vevay, which is the same as that of Geneva, amounts to 

 372 metres, that district must have undergone a sinking of 

 1468 metres. If we assume the same amount of sinking for the 

 Alps, Mont Blanc must have had a height of 6278 metres, an 

 elevation not nearly equal to that of the highest summits of the 

 Himalaya, of the Nevados of Illimani and Sorata, or of Chim- 

 borazo. 



