3 3 o SCIENCE PROGRESS 



had then already attained there a thickness of some 5,000 ft., and 

 overflowed the Grimsal pass. Farther down, where the Visp 

 and Saas glaciers entered, it was even thicker. Filling the 

 valley, it pursued its course past the bend at Martigny, and 

 emerged from the Alps to overwhelm, in a great fan-shaped 

 expansion, all the region now occupied by the lakes of Geneva 

 and Neuchatel ; it rose against the flanks of the Jura to a height 

 which shows it to have possessed even at this distance from its 

 source a thickness of 4,600 ft. But it did not terminate here ; it 

 surmounted the Jura, and debouched on the plains of France. 

 There it deposited its terminal moraine, which runs in a much 

 indented, but on the whole crescentic, line from Videnne, 

 through Lyon, past Villefranche, to Villereversure, Arlay, 

 Mesnay, Morteau, till it re-enters Swiss territory, between 

 Maiche and Seignelegier, to become continuous farther on with 

 the similar moraine of the great Rhone glacier. 



As might have been expected, this increase in volume was 

 not confined to the glaciers of the Rhone valley. All the glaciers 

 of Switzerland were affected in a corresponding degree ; and the 

 whole of this territory, now dotted over with numberless farms 

 and villages and with great towns like Zurich and Geneva, was 

 buried beneath a continuous sheet of snow and ice. 



It is not necessary to visit Switzerland to become familiar 

 with the signs left by the ancient ice of the Glacial epoch ; they 

 surround us on every hand at home, and are amongst the 

 commonest features of the mountainous parts of our land. 

 Smoothed and striated surfaces, boulder clay and superficial 

 morainic material, testify to the passage of the ice, indicate its 

 direction, afford evidence of its thickness, and determine its 

 boundaries. If we follow the southern boundary of the ice, we 

 shall find that it will take us out of Britain and lead us right 

 across the continent of Europe. After stretching from Kerry 

 to Wexford, and through the Bristol Channel to London, it 

 crosses the sea, continues its course through Antwerp, past 

 Magdeburg, Cracow, Kiew, runs south of Moscow to Kazan, 

 and then terminates at the southern end of the Ural mountains. 

 All that lies to the north of this line — the greater part of the 

 British Isles, Northern Germany, Scandinavia, and almost the 

 whole of European Russia — was buried out of sight beneath a 

 mantle of ice formed by the confluence of many colossal glaciers. 



At the same time a large part of North America was 



