ALPINE VEGETATION. 205 



the streams flowing from the glaciers, into the low country, 

 where they established themselves in the vicinity of the glaciers 

 and moraines. The Albis, the Uetliberg, the Zurichberg, and 

 indeed all the chains of hills lying above the glaciers were pro- 

 bably covered with forests, as are now the slopes surrounding 

 the Bernina glacier, and many other districts into which great 

 glaciers descend. 



From the time of the greatest extension of the glacier in the 

 Canton of Zurich to the epoch of its retreat from the district, all 

 degrees of transition occurred ; and, on the hypothesis of two 

 glacial periods, these intermediate stages were repeated more 

 than once. A similar alternation is implied in the conditions 

 of temperature. At the time of the greatest extension of the 

 glaciers the temperature must have been at its lowest point ; it 

 must then have risen again ; and the vegetation must have fol- 

 lowed these changes. It is to be supposed that in the coldest 

 period of glacial action the spots free from ice and snow were 

 covered with a vegetation like that which is now seen on the 

 Swiss Alps ; and as the glaciers afterwards retreated these plants 

 also retired up into the mountains, and other vegetable forms 

 occupied the vacant places in the plain. Just as the Swiss 

 Alpine plants now fringe the fields of granular snow, and live 

 on moraines and glacier-islets, adorning them with the most 

 charming colours, so they formerly accompanied the glaciers 

 down into the lower country, presenting the same phenomenon 

 that may still be witnessed in Iceland and Greenland, where the 

 Alpine flora descends with the glaciers even to the sea-coast. 



Unfortunately organic remains of the Glacial period have 

 reached modern times in very scanty measure, which is probably 

 due chiefly to the unfavourable nature of the deposits of this 

 epoch for their preservation. 



Of plants, only a few fir-cones (Pinus Abies, Linn.) are known, 

 which Prof. Morlot has found in the glacial debris of Thonon 

 and in a lignite-like formation near the Signal of Bougy, with a 

 species of moss (Hypnum diluvii, Schimp.) . The fir-cones teach 

 us that at the time when the glacier extended down as far as 

 the Lake of Geneva there must have been forests of firs in that 

 vicinity ; and the moss is most nearly allied to a species from 

 Lapland and of the Sudetes (H. sarmentosum} . 



