i psn 
Physical Theory of Secular Changes of Climate. 485 
become covered with vegetation and stocked with animal 
ife.” 
Let us now see to what all this leads. It has been proved 
beyond the possibility of a doubt that, at the time the till 
was being formed which overlies the Scottish interglacial beds, 
the whole of Scotland, Scandinavia, the bed of the North Sea, 
and a great part of the north of England was covered with 
Baltic, overflowed Denmark and Holstein, and advanced into 
North Germany as far at least as Berlin. It has also been 
) 
Reap fauna as that of the Selsea bed, where it is mixed 
up with the remains of some of those pachyderms, as well as 
of some other features, it has seemed to me that the climate of 
the earlier part of the Post-glacial Period in England was pos- 
sibly even warmer than our present climate; and that it was 
Succeeded by a refrigeration sufficiently severe*to cause ice to 
form all round our coasts, and glaciers to accumulate in the 
valleys of the mountain districts.’ That these faune indicate 
4 warm and equable condition of climate is further evident 
from Mr. Wallace’s remarks: “The fact,” he says, “of the 
hippopotamus having lived at 54° north latitude in Eng- 
land, quite close to the time of the Glacial Epoch, is absolutely 
inconsistent with a mere gradual amelioration of climate 
