Ancient Extent of the Glaciers of Chamonix. hi 



way : ** To study tlie mo(Je of action of natural elements which 

 we witness before our eyes, and compare the effects they 

 produce with those of which traces are still preserved on the 

 surface of the globe.'' By proceeding on this principle, we 

 shall find that we can discover everywhere, in the vast plains 

 which surround the Alps, traces of those gigantic glaciers of 

 which such as now remain may be said to be the mere mi- 

 niatures. Still, although reduced to small dimensions, exist- 

 ing glaciers present us, on a small scale, with all the pheno- 

 mena that formerly occurred in fields of ice on a large scale. 

 The effects are the same, and we can infer their identity from 

 that of the agents which have produced them. 



1 . Of Existing Glaciers. 



From the summit of the ridge of the Jura, which over- 

 looks the Leman basin, we obtain a bird's-eye view of the 

 whole chain of the Alps, from the Valais to Dauphiny. The 

 colossal mass of Mont Blanc, resting on its broad base, 

 rises majestically and alone above this long serrated ridge. 

 The highest peaks are distinguished from the less elevated 

 summits, by the sparkling whiteness of the snow which covers 

 them. In summer, the lower limit of these perpetual snows 

 forms a straight horizontal line, perfectly marked, which 

 contrasts with the sombre verdure of the forests along the 

 base of the mountains. This line is that of eternal snows. 

 Above it, winter reigns alone ; below it, the seasons follow 

 their regular course. Above it, life scarcely exists, and is 

 represented only by a few polar plants, and some ephemeral 

 insects ; below, it is manifested in a thousand varied forms, 

 from the highest regions where the pine and the chamois ven- 

 ture to appear, down to the plains inhabited by man, where 

 the harvests become yellow, and the vine ripens its fruit. 



In Switzerland, the lower limit of perpetual snow is about 

 2700 metres above the level of the sea ; but as we approach 

 the Alps, penetrating into the narrow valleys which inter- 

 sect the principal masses, such as those of Mont Blanc, Mont 

 Rosa, St Gothard, and the Jungfrau, we perceive that this 

 limit is not a straight line, as it appeared when seen at a 

 distance. The fields of perpetual snow emit branches, so to 



