2 48 PREHISTORIC EUROPE. 



and in latitudes where at present the temperature rarely or never 

 descends to the freezing-point were broken up, fractured, ana 

 displaced, and long trains of coarse angular debris gathered upon 

 the hill -slopes, from which n4v6 and melting snow and torrent? 

 carried them down to the plains and caused them to overspread 

 wide areas. Everywhere the forces of denudation were energeti- 

 cally at work. In summer the valleys were filled to overflowing 

 with vast floods discharged from melting snows and glaciers. 

 Enormous stretches of low ground, especially in Southern Eussia, 

 were converted into broad inundation-lakes, from the muddy 

 waters of which an abundant precipitation of fine sediment took 

 place. All these facts compel us to admit that the climate of 

 Europe during the Glacial Period experienced a general refri- 

 geration. The winters were unquestionably more severe, but 

 we are not to suppose that the conditions were equally extreme 

 throughout the Continent. The northern latitudes and the 

 higher elevations were then as now subject to keener cold than 

 the lower-lying and more southern regions. The temperature 

 of the air in summer would be kept low by the presence of the 

 great snow-fields and glaciers and ice-cold rivers and inundation- 

 waters, so that although the heat received directly from the sun 

 during that season may have considerably exceeded that which 

 reaches us now, still the climate would not be such as to encou- 

 rage the growth of a temperate flora in Central Europe. Looking 

 at the physical conditions which then obtained in our continent, 

 we may reasonably infer that the only flora which could have 

 occupied Central Europe during the climax of the Ice Age must 

 have been the Arctic willows and dwarf birches, the mosses, 

 lichens, and saxifrages, which are now banished to mountain- 

 heights and high latitudes. The pines and firs which adorn so 

 many of our alpine regions must have descended then to the low 

 grounds at the base of the mountains, while the great bod} r of 

 the temperate flora — the oaks, beeches, elms, poplars, etc., with 

 their humbler congeners — driven in large measure from the lati- 

 tudes which they now characterise, would spread into more 

 southern climes. It would be with the animals as with the 



