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POPULAR SCIENCE REVIEW. 
type of mammalia. The Glacial Epoch came on, and for long 
ages the forest of Cromer and its lake bed and the skeletons 
of the animals which had been washed into it, were sunk beneath 
the waters of the glacial seas and were covered up by these 
relics of floating ice, the erratics from the distant north. Then, 
in days long after, we find the forest animals succeeded by a 
northern group of animals — the mammoth, the lemming, the 
reindeer — which had to migrate for shelter and food from regions 
which had become uninhabitable through the rigour of intense 
frost, and where no longer could flourish even the arctic willow 
or the reindeer moss. And it was then that the vegetation of 
Great Britain became changed also. Here, then, grew the food 
of the reindeer, and the arctic birch flourished where many a 
plant had to yield before the influences of frost ; and the dwarf 
willow, which we now find upon our highest hill summits, 
among glacier tracks and the groovings of extinct ice, must 
have grown abundantly by the caves which, in so many parts of 
England, yield the fossil bones of the reindeer, the mammoth, 
and the Irish elk. 
But if this is the history of temperate latitudes, what has 
been the effect of frost and icework in northern regions ? There 
was a time when Greenland and Spitzbergen were not under 
the dominion of frost as they are now, but when luxuriant 
forests grew where now sweeps the glacier, and the vine flourished 
upon sites now sealed by ice which no summers’ sun can melt. 
The researches of geologists have revealed to us that this now 
icebound continent was, in Tertiary times (Miocene ages), a 
forest land, stretching away towards the Pole on the north, and 
to Spitzbergen on the east. Among the trees of this Green- 
landic vegetation was a large Sequoia, closely allied to the great 
Californian pine, the Wellingtonia gigantea, which is found fossil 
where it grew, its roots in the soil, and around its branches, its 
leaves, and cones. This tree is very abundant in the lignite beds. 
The chestnut-tree has been determined, with its flowers and its 
fruit. There, too, grew the magnolia, of which both the flowers 
and cones have been preserved, the walnut, the plane-tree, and 
the vine. There were eight species of oak, the birch, the hazel, 
and the alder ; and beneath these forest trees grew numerous 
ferns, while the stems of the trees were twined around by the 
ivy and the vine. Even the fungi on the leaves of certain trees 
have been detected by their spots and dots and spores, which 
are determinable under the microscope. Well, then, may we 
inquire into the cause of this wonderful change brought about 
by the frost and cold of the Glacial Epoch since Miocene times 
in Polar regions ; as well as to the cause which brought about 
the Ice history among our own mountains and valleys of Great 
Britain. 
