338 THE BRITISH ISLES. 



But the rocks detiched by glacial action from tbo summits of the Grampians 

 were not all deposited at the foot of the glaciers. There was a time, during the 

 great ice ago, when a large portion of Great Britain was submerged beneath the 

 waters of the Atlantic, and icebergs, cast off by the Scotch glaciers, carried rocks 

 and other débris to considerable distances. Only in this way can we explain the 

 presence of Scotch granite in the clay of "Wolverhampton and near Worcester, at 

 a distance of 170 and '200 miles from the mountains whence these erratic blocks 

 can have been derived.* The Hebrides, too, formerly much less elevated than 

 they now are, were planed by icebergs floating across the Minch.f But whilst 

 Caledonia sent its rock-laden icebergs to immense distances, it became in turn 

 the depository of erratic blocks detached from the mountains of Scandinavia. 

 In the county of Aberdeen, and in other parts of Scotland, -Norwegian granite 

 occurs in immense quantities. At various places the glacial streams descending 

 from the Scotch and the Scandinavian mountains appear to have met, and 

 deflected each other. The glacial scorings on the rocks of Caithness, for instance, run 

 from the south-east to the north-west, instead of from south to north, in accordance 

 with the direction which the icebergs took when first they started upon their 

 pilgrimage. This deflection, however, is explained if we assume that they 

 encountered an easterly current laden with Scandinavian ice, and were consequently 

 drifted to the north-westward. Similar scorings, traceable to the agency of 

 Scandinavian ice, have been discovered on the rocks of the Orkneys, Shetland 

 Islands, and Fiirder.J 



Oscillations of the soil succeeded each other in Caledonia in the course of 

 geological periods. Near Grangeraoutb the bed of an ancient river has been 

 discovered at a depth of 2G0 feet beneath the Forth, and this proves that the 

 country must have subsided to that extent since this river flowed across it.^ 

 So considerable and unequal have been the changes of level that boulders of 

 granite are found now at a height greater than that of the movmtains from 

 which they were originally detached. The most recent phenomenon of this 

 nature is that of a gradual upheaval of the laud. It is owing to this upheaval 

 that the share which the glaciers of Norway had in the formation of Scotland 

 has been revealed to us. Along all the coasts may be observed raised beaches 

 covered with marine shells, some as regular in their contours as if the sea had 

 only recently retired from them, others ravined by torrents, and here and there 

 covered with débris. At a height of 43 feet above the actual level of Loch 

 Lomond can be traced one of these ancient beaches, which must have been formed 

 when that loch was still an arm of the sea, and freely communicated with 

 the ocean. The erratic blocks stranded on the raised beaches of some parts of 

 the coast resemble rows of penguins perched on a projecting terrace. Along the 

 coasts of Aberdeen and Caithness these ancient beaches vary in height from 

 10 to 160 feet, and their elevation gradually diminishes as we proceed north- 



• Mackintosh: Symonds Qnarterh) Journal of the Geological Society, l^ovQmher, 1877. 

 t James Gcikif. " History of a Boulder." 

 X James Croll, " Climate and Time." 

 § James Geil;ie, " The Great Ice Age." 



