540 R. Mountford Deeley—The Ice Age 
a great portion of the piedmont it formed, were alimentation areas. 
The ice had to spread as far as Lyons before a sufficiently large 
ablation area could be formed to enable the warm air and rain of the 
lower regions to melt the ice completely. 
Penck & Bruckner’ express themselves to the following effect : 
‘“The Alps during the Ice Age appeared essentially different to the 
Greenland of to-day. They bore no inland ice. In the interior of 
the mountains there was no continuous névé field. The individual 
glaciers were very similar to those of the present day—widely 
separated from one another by mévé ridges, which are not to be 
compared with the nunataks of Greenland. The ice-stream network 
showed, therefore, a similar slope development to the Greenland inland 
ice; it formed in the middle a smooth arching shield, which became 
steeply bent at the margin. But above this shield still rose the névé 
ridges, in the North Tyrol by about 1,000 to 1,500 metres, in 
Switzerland in places by about 2,000 or even 2,500 metres, and from 
these névé ridges separate glaciers sank down to the ice-stream 
network, usually with extreme steepness, but at times with gentle 
gradient. The Ice Age glaciers displayed a swelling of the tongues, 
but not at the same time a swelling of the névé fields of the present 
glaciers. Now if during the Ice Age the névé fields were no fuller 
than now, we cannot ascribe the glacier development during the Ice 
Age, compared with that of the present day, to an increase in 
precipitation, but must trace it to a decrease of ablation.” 
The question of the climatic conditions of the Ice Age will be 
found to have been very fully discussed by Penck & Bruckner as far 
as the Alps are concerned. They are decidedly of opinion that 
the phenomena exhibited in this area show that the Ice Age was 
essentially one of low temperature, not of increased precipitation. 
They conclude that at the culmination of the Glacial period the 
snow-line stood at an altitude of 1,200 metres below the present 
snow-line, and that the frost period at this low level was of equal 
duration to that which exists at the present snow-line. Such 
a fall of the snow-line would enormously increase the alimenta- 
tion areas. 
From a comparison of the Ice Age snow-line with that of the present 
day Penck & Bruckner also conclude that the general winds of the 
Ice Age blew, as regards direction, much as they do now, for, from the 
close relationship between the height of the snow-line during the Ice 
Age and the present distribution of precipitation, they hold that 
during the Ice Age a similar distribution of precipitation existed as 
at the present day; that in particular also at that time the rain- 
bringing wind was the west wind, and that the ‘adria’ bestowed on 
the south-east angle of the Alps abundant precipitation. 
At the present time the snow limit, although of variable height on 
the same latitude, is higher in the Tropics than it is in the Frigid 
regions. But it is also often lower where the precipitation is 
greatest. Thus we have in the Andes a lower snow-line where the 
precipitation is greatest. North and south of this point the snow-line 
1 The Alps in the Ice Age, p. 1141 et seq. 
