424 Climate of the Glacial Period. (October, 
Norfolk, and thrust up great masses of chalk and other 
angular rocks upon the land. We have a measure of its 
thickness in Southern Yorkshire, and learn that it was not 
so deep on the eastern as it was on the western side of 
England, for the drift does not reach higher than 600 feet 
above the sea, excepting where the Wye, the Calder, and 
the Aire cut through the Pennine Chain, and form passes 
through which the ice streamed from the west, where it was _ 
much higher. The Irish Sea was filled with it, flowing 
southwards, at least 2000 feet thick. It butted against the 
Welsh mountains, and, dividing, one part pushed up the 
valleys of the Mersey and the Dee, and through what has 
been called the Straits of Malvern, certainly as far as the 
water-shed of the Severn, probably as far as the Bristol 
Channel; the other and larger stream, shouldering the 
western slopes of the mountains of Cardiganshire, flowed 
across Anglesea to the Atlantic. In Ireland the ice was 
still thicker, and Mr. Campbell considers that in the extreme 
south of that island he has obtained proofs of it having been 
at least 2000 feet thick. This thickening of the ice west- 
ward proves that the British Isles were not glaciated from 
Scandinavia. 
Passing across to the continent we find Scandinavia hugely 
glaciated, and that the ice-sheet that flowed from it filled the 
Gulf of Bothnia and the Baltic. Denmark was assailed by 
the advancing ice, and everywhere traces are left of its vast 
extent and force. Inthe island of Moen the chalk strata 
are dislocated and folded together, inclosing in their folds 
patches and seams of boulder clay. The Danish geologists 
have ascribed these to a faulting and bending of the strata 
since the Glacial period; but both in Nova Scotia and at 
Abergairn, in Aberdeenshire, I have seen great masses of 
strata that have been pushed along horizontally over others 
by the great force of the advancing ice, and think that the 
post-tertiary contortions of the strata in Moen must be due 
to the same agency. After crossing the Baltic the ice crept 
southwards, and all over northern Germany and Holland 
blocks of stone strew the surface that have been brought by 
it from the mountains of Norway and Sweden. It 
reached its southern limit somewhere about Antwerp, and 
eastward the range of the northern drift has been traced to 
an irregular line across the Continent. In European Russia 
the ice reached to Nijni Novgorod, in lat. 52°; to which 
parallel I have also traced it in north-western Asia, near 
Pavlodar, in Siberia, and in a paper read before the Geolo- 
gical Society of London have described the facts that have 
