THE TUNDRAS AND STEPPES OF PREHISTORIC EUROPE. 345 



These conditions were rendered possible by the former greater extension 

 of our continent into the Atlantic, when the major portion of the North 

 Sea and the English Channel were dry land, and the British Islands 

 formed part of the continental area. 



Considerable climatic changes continued to take place after the pass- 

 ing of the third glacial epoch. These have left their traces in the 

 alpine lands, but they are nowhere so clearly seen as in northern and 

 northwestern Europe. Temperate conditions supervened in north 

 Germany, the flora and fauna closely resembling those of the present. 

 But eventually a relapse to glacial conditions followed, and from the 

 Scandinavian snow fields another invasion of north Germany took 

 place. Norway, Sweden, and Finland were now once more shrouded 

 in ice, and a great Baltic glacier came into existence, the gigantic ter- 

 minal moraines of which are met with in Denmark, Schleswig-Holstein, 

 and Prussia. The Scottish Highlands and other mountainous parts of 

 the British Islands at the same time nourished local ice sheets and 

 large valley glaciers, which in many cases descended to the sea. The 

 alpine lands in like manner witnessed a recrudescence of glaciation, 

 large glaciers flowing into the great longitudinal valleys, but nowhere 

 deploying as before upon the low grounds. It is to this stage, proba- 

 bly, that Ave should assign the tundra fauna of the Schweizersbild. 

 (See Map D.) 



The succession in that interesting rock shelter has shown that as the 

 severity of the climate relaxed, steppe and forest faunas successively 

 followed the disappearance of the tundra forms. The climate of Europe 

 generally became temperate, and immense forests overspread wide 

 regions. It was during the approach of these conditions, as we have 

 seen, that Paleolithic man seems finally to have vanished and the 

 Neolithic races to have made their earliest appearance in Europe. The 

 British Islands at this time formed part of the continent and the Baltic 

 existed as a great fresh- water lake. The lower buried forests of our 

 peat bogs are among the conspicuous remains of this stage. Eventually, 

 however, submergence ensued, the British Islands were severed from 

 the continent, and the sea again invaded the Baltic basin. It is nota- 

 ble that the character of the marine fauna which at this stage lived off 

 the coasts of Scandinavia and Britain is indicative of more genial con- 

 ditions than now obtain. The climate, however, gradually became 

 colder, the vertical and horizontal range of the forests was restricted, 

 and snow fields again appeared among the higher mountains of our 

 islands. In Scotland glaciers here and there came down to the sea, 

 and dropped their moraines upon the beaches then forming; the large 

 majority, however, terminated inland. At that time the snow line in 

 north Britain ranged between 2,000 and 2,600 feet. Similarly, in Nor- 

 way and in the Alps an advance of glaciers took place — the snow line 

 in southern Norway being about 2,400 feet, while in the alpine lands 

 it seems to have averaged 7,500 feet, or some 1,600 feet lower than the 

 present. 



