18401881] EARTH-MOVEMENTS 121 



effected during a vast (almost gratuitously assumed) slow Letter 482 

 Tertiary subsidence and subsequent Tertiary oscillating 

 slow elevation. So our high cliff argument is inapplicable. 

 He seems to think his great subsidence only favourable for 

 great denudation. I believe from the general nature of the 

 off-shore sea's bottoms that it is almost necessary ; do look at 

 two pages p. 25 of my S. American volume on this subject. 1 



The foundation of his views, viz., of one great sudden 

 upheaval, strikes me as threefold. First, to account for the 

 great dislocations. This strikes me as the odder, as he admits 

 that a little northwards there were many and some violent 

 dislocations at many periods during the accumulation of the 

 Palaeozoic series. If you argue against him, allude to the 

 cool assumption that petty forces are conflicting : look at 

 volcanoes ; look at recurrent similar earthquakes at same 

 spots ; look at repeatedly injected intrusive masses. In my 

 paper on Volcanic Phenomena in the Geolog. Transact? I have 

 argued (and Lonsdale thought well of the argument, in 

 favour, as he remarked, of your original doctrine) that if 

 Hopkins' views are correct, viz., that mountain chains are 

 subordinate consequences to changes of level in mass, then, 

 as we have evidence of such horizontal movements in mass 

 having been slow, the foundation of mountain chains (differing 

 from volcanoes only in matter being injected instead of ejected) 

 must have been slow. 



Secondly, Ramsay has been influenced, I think, by his 



1 Geological Observations on S. America, 1846, p. 25. "When 

 viewing the sea-worn cliffs of Patagonia, in some parts between 800 and 

 900 feet in height, and formed of horizontal Tertiary strata, which must 

 once have extended far seaward ... a difficulty often occurred to me, 

 namely, how the strata could possibly have been removed by the action 

 of the sea at a considerable depth beneath its surface." The cliffs of 

 St. Helena are referred to in illustration of the same problem ; speaking 

 of these, Darwin adds : " Now, if we had any reason to suppose that 

 St, Helena had, during a long period, gone on slowly subsiding, every 

 difficulty would be removed ... I am much inclined to suspect that we 

 shall hereafter find in all such cases that the land with the adjoining bed 

 of the sea has in truth subsided . . ." (loc. cit., pp. 25-6). 



2 " On the Connection of certain Volcanic Phenomena, and on the 

 Formation of Mountain-chains and the Effects of Continental Itlevations." 

 Geol. Soc. Proc., Vol. II., pp. 654-60, 1838 ; Trans. Gcol. Soc., Vol. V., 

 pp. 601-32, 1842. [Read March ;th, 1838.] 



