218 GEOLOGICAL TIME 



indeed, to have been still more gigantic than these. 

 It may be doubted, for example, whether among the 

 vestiges that remain of Mesozoic or Palaeozoic 

 mountain-chains, anv instance can be found so colossal 

 as those of Tertiary times, such as the Alps. No 

 volcanic eruptions of the older geological periods can 

 compare in extent or volume with those of Tertiary 

 and recent date. The plication and dislocation of the 

 terrestrial crust are proportionately as conspicuously 

 displayed among the younger as among the older for- 

 mations, though the latter, from their greater antiquity, 

 have suffered during a longer time from the renewed 

 disturbances of successive periods. 



As regards evidence of greater violence in the 

 surrounding envelopes of atmosphere and ocean, we 

 seek tor it in vain among the stratified rocks. One 

 ot the very oldest formations in Europe, the 

 Torridon Sandstone of North-West Scotland, presents 

 us with a picture of long-continued sedimentation, 

 such as may be seen in progress now round the shores 

 of many a mountain-girdled lake. In that venerable 

 deposit, the enclosed pebbles are not mere angular 

 blocks and chips, swept by a sudden flood or destruc- 

 tive tide from off the surface of the land, and huddled 

 together in confused heaps over the floor of the sea. 

 They have been rounded and polished by the quiet 

 operation of running water, as stones are rounded 

 and polished now in the channels of brooks or on 

 the shores of lake and sea. They have been laid 

 gently down above each other, laver over layer, with 

 fine sand sifted in between them, and this deposition 

 has taken place along shores which, though the waters 



