COLD AND ICE ON THE EARTH 



which is produced by a glacier, because the river tosses the 

 rocks and stones in all directions, polishes them on every 

 side, and leaves no distinctive parallel scratches or grooves 

 on them. That can only be done by glaciers which hold 

 the rocks, the rubbers and the rubbed, pressed firmly 

 together and grind them continually in the same way. 



These scratchings or striations of rocks, the smoothed 

 and grooved surfaces, and the deposited boulder-clay and 

 boulders enable us to trace the march of great ice-sheets 

 over regions of the earth which are now of totally 

 different aspect. From this kind of evidence we have 

 been able to find that the whole of Northern Europe was 

 once buried under a great expanse of snow and ice. The 

 sheet was, as we should expect, thickest in the north and 

 west, and thinned away southward and eastward. Over 

 Scandinavia it was between 6000 and 7000 feet in 

 thickness as we can tell from the scratches on the sides 

 of the high mountains. Similar marks 3000 feet above 

 the sea-level in the Scottish Highlands lead us to believe 

 that over Scotland the glaciers were 5000 feet thick, and 

 even as far south as the Hartz Mountains in Germany 

 it could not have been far short of 1500 feet in thickness. 

 Imagine this great mass of ice ever slowly moving and 

 ever creeping solemnly down to the sea. By the markings 

 it left we can trace where the greater glaciers slid grandly 

 along. In Scandinavia it swept westwards to the Atlantic 

 and eastwards to the Gulf of Bothnia, then frozen as 

 solid as the Pole. Southward the ice ground its way 

 across Denmark to the Low Countries and North Ger- 

 many. The Baltic was choked with ice, and so was the 



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