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120 Africa. During the period of maximum cold, the glaciers of Auvergne joined those of the Jura, in the valley of the Rhone, and those of the Alps extended far down into Lombardy, France, Switzerland, and Germany. From the Pyrenees, also, glaciers found their way as far as Toulouse, and from the snowy tops of the Atlas and of the Lebanon they descended to the level of 6000 feet, and from the mountains of Lazistan to that of 4500 feet above the sea.

This period of maximum cold in the south of Europe coincided with a period of high elevation, in which the Mediterranean area was lifted up not less than 2400 feet above the sea, so as to allow of Europe joining Africa by way of Gibraltar and of Sicily and Malta, as we have seen in this chapter. The Alps also, at the beginning of the Pleistocene, according to Professor Gastaldi, stood 1312 feet higher than they were in the Pleiocene age.

These climatal changes are traceable in the Alps by the advance and retreat of the glaciers, and in some Alpine districts there is evidence of a reversion to a temperate climate. On the borders of the lake of Zurich, for example at Utznach and Dürnten, a bed of lignite intercalated between two glacial accumulations proves that a forest occupied the same tract of ground which before and after was covered by a glacier.