﻿MURCHISON — FLINT DRIFT OF S.E. ENGLAND. 395 



Nor have we, in discussing the question of the Wealden denuda- 

 tion and the formation of its local drift, the power of invoking the 

 agency of ice, as in the more northern tracts of England and Scot- 

 land and over large portions of Ireland. Here we cannot appeal to 

 terrestrial or sea-borne ice, to get rid of the difficulty of tumultuous 

 accumulation, by supposing that icebergs impinged upon alluvial 

 matter. For no one has yet ventured to suggest, that the heights of 

 Butser, Hind Head, or Leith Hill were the abodes of glaciers, nor 

 has any one detected appearances in the drift within or without the 

 Wealden area which can be considered to have resulted from the 

 mechanical action of ice ; still less have any species of arctic shells 

 or far-transported blocks ever been observed within the area affected. 



The natural impression, therefore, is, that the last great ruptures and 

 denudation of the Wealden being completed, this tract was shut out 

 and excluded from the influence of that boreal sea, of whose former 

 effects, including the powerful operation of floating ice and frozen 

 mud and stones, there are such clear signs over wide spaces in Scot- 

 land, Ireland, and Wales, as well as over large northern portions of 

 the Continents of Europe and America. 



Such general drifts are to be considered as distinct from the local, 

 angular flint-drift of the South-east of England. 



In sustaining these views, I have simply endeavoured to substan- 

 tiate by an appeal to physical evidences, that, as many species of qua- 

 drupeds doubtlessly passed away by gradual extinction and long-con- 

 tinued ordinary causation, others were suddenly destroyed by local 

 oscillations and violent fractures of the crust of the earth, and were 

 entombed in drift accumulated under transient volumes of water. For, 

 whilst it is our special duty as geologists to examine the drifted mate- 

 rials of each country in reference to its own phenomena, we must not 

 forget that the very same species of fossil quadrupeds, as those to 

 which I have been adverting, have also been buried in the gold- 

 bearing drift of the Ural Mountains and Siberia, as well as in the 

 coarse detritus of similar age covering other large portions of the world, 

 which also has been accumulated under a much more powerful agency 

 and much more copious volumes of water than have since affected 

 those lands. It is manifest, therefore, that however the subsidiary 

 causes may have been local and diversified, there was a very general 

 destruction of great terrestrial animals during the period in question. 

 In a word, Geology teaches that slow and long-continued accumula- 

 tions have been succeeded at various epochs by violent dismember- 

 ments, and it is to one of the last of these periods of great revolution 

 that attention is now directed. 



Postscript. 



Although I have expressed my opinion, that the upper heaps of 

 unstratified, angular, or unrolled flints, which vary in thickness 

 from 2 and 3 to 25 feet, resulted chiefly from one operation, I fully 

 admit, that in some situations (particularly along the Sussex coast) 

 the lower members of the drift have been accumulated under aqueous 



