36 
POPULAE SCIENCE EEVIEW. 
England; and_, towards its close^ tlie great continent formed 
by the upheaval of the Miocene tertiaries, was gradually 
destroyed. Ireland was separated from Spain^ and the dis- 
junction of the south-east of Ireland and south-west of 
England from the Channel Islands and the adjacent coast 
of France was effected. The unshaded and most deeply 
shaded parts of Plate II. enclosed the whole of the area of 
Ireland and Great Britain then visible. 
To this period succeeded the Glacial Epoch. The climate of 
the northern hemisphere^ which had been during the Tertiary 
Epoch considerably warmer than it is now^ became, towards 
its close, much colder, in consequence of the gradual accnmn- 
lation of snow and ice at the poles. The ice-formation mani- 
festly began about this time ; for, as we go further back into 
the history of the earth through the Tertiary deposits, we 
find neither erratic blocks nor any indications of the marks of 
glaciers; on the contrary, the proofs become more and more 
apparent that the climate, in these earlier epochs, was much 
warmer than it is at present. Hence, the appearance of ice 
at the poles and on the summits of the mountains must be 
regarded as, comparatively speaking*, a recent event in the 
history of creation, and is contemporaneous with some of the 
last revolutions to which the earth has been subjected. 
During the Glacial Epoch the whole of the northern portion 
of Europe was covered by the German Ocean, which extended 
itself from the Alps of Switzerland to the Uralian Mountains 
Df Bussia, and covered all that portion of the British Isles and 
the adjacent coast of France, numbered lY. in Plate II. The 
tops of the mountains of Scandinavia, Wales, and Scotland — 
(the area of the two last lightly shaded, and numbered III.), were 
then low islands. The climate was much colder than it is now, 
similar to that in the north-east coast of America, in the same 
latitudes, and presenting very similar phenomena. It was a 
region of fog*, floating icebergs, and boulders, which are able 
to transport both seeds and plants. With such means of 
transport existing in abundance around them, Scotland and 
Wales now received their Arctic flora from Scandinavia. 
This Glacial Epoch was again succeeded by another, and at 
its close Europe presented quite a different appearance. The 
bed of the glacial sea was elevated. Sweden, Horv/ay, Lap- 
land, and the whole of the northern portion of Bussia, and all 
the parts of England, Ireland, and the adjacent coast of France, 
numbered IV., were formed. In fact, the land was continuous 
from the western coast of Ireland across the sites now occupied 
by the Irish Sea and the German Ocean, to Germany and Bussia. 
Those parts of Scotland, Wales, and Scandinavia formerly low 
islands in an icy ocean, now underwent elevation, and were 
