232 THE GLACIAL OB ICE EPOCH. 



higher latitudes of Europe, Asia, and North. America, the 

 regions within which the phenomena of the glacial epoch 

 are most strikingly displayed, and to which (from the 40th 

 or 42d parallel northwards) they were in all likelihood re- 

 stricted. Over these limits the ice-epoch long held its iron 

 sway, annihilating, or all hut annihilating, terrestrial life ; 

 grinding, and rounding, and moulding the land-surface as 

 no other agent but ice can do ; and loading the bottom of 

 the ocean with miscellaneous masses of mud, shingle, and 

 boulders. This paucity of life, these land-surfaces, and 

 these miscellaneous accumulations, are the principal proofs 

 of the conditions of the glacial epoch, and these we must 

 first consider under the knowledge we have gained by a 

 perusal of the preceding chapter. 



At first it seems evident that towards the close of the 

 tertiary period the climate of a large portion of the northern 

 hemisphere was gradually growing colder and colder. In 

 all likelihood the land was somewhat higher than it is 

 now, and as this cold increased the loftier mountains would 

 become perennially enveloped with snow and glacier, arid 

 the surrounding seas with an annual covering of ice. Un- 

 der this increasing rigour all the more delicate tertiary 

 plants and animals would succumb, and those endowed 

 with greater elasticity of constitution would shift ground 

 to lower and more southern situations. As the cold still 

 increased, the ice-sheet seems to have spread itself even over 

 the lower grounds, to have pushed its way out to sea, and 

 during the thaw and currents of a brief summer to have 

 been drifted off in floes and bergs, as the ice is now from 

 the coasts of the arctic and antarctic regions. At this stage 

 the terrestrial flora and fauna would be at their minimum, 

 and paralleled, perhaps, by what we now find in Greenland 

 and the islands of the Arctic Ocean. During this setting-in 



