462 Notices of Memoirs — British Association — 



mere theoretical possibility. Such evidence, if it existed, couhl 

 surely be produced. The chronicle of the earth's history, from a very 

 early period down to the present time, has been legibly written 

 within the sedimentary formations of the terrestrial crust. Let the 

 appeal be made to that register. Does it lend any support to the 

 affirmation that the geological processes are now feebler and slower 

 than they used to be ? If it does, the physicists, we might suppose, 

 would gladly bring forward its evidence as irrefragable confirmation 

 of the soundness of their contention. But the geologists have found 

 no such confirmation. On the contrary, they have been unable to 

 discover any indication that the rate of geological causation has ever, 

 on the whole, greatly varied during the time which has elapsed since 

 the deposition of the oldest stratified rocks. They do not assert 

 that there has been no variation, that there have been no periods 

 of greater activity, both hypogene and epigene. But tliey maintain 

 that the demonstration of the existence of such periods has yet to be 

 ■made. They most confidently affirm that whatever may have 

 happened in the earliest ages, in the whole vast succession of sedi- 

 mentary strata nothing yet has been detected which necessarily 

 demands that more violent and rapid action which the physicists 

 suppose to have been the order of nature during the past. 



So far as the potent effects of prolonged denudation permit us to 

 judge, the latest mountain upheavals were at least as stupendous 

 as any of older date whereof the basal relics can yet be detected. 

 They seem, indeed, to have been still more gigantic than those. It 

 may be doubted, for example, whether among the vestiges that 

 remain of Mesozoic or Palseozoic mountain-chains any 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 

 formations, 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 for it in vain among the 

 stratified rocks. Among the very oldest formations of these Islands, 

 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 destructive 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, layer over 

 layer, with fine sand sifted in between them, and this deposition has 

 taken place along shores which, though the waters that washed them 



