Rev. 0. Fisher — Glacial Action and Raised Sea-heds. 165 



the "weight of the hill," that is of the tendency of the surface to 

 slip downwards under the influence of frost, might be applied. 



In none of these cases is there any Boulder-till properly so called 

 in the vicinity. 



This phenomenon, and also the Trail, have no doubt an important 

 bearing upon the great question of denudation. I have attributed 

 them to glacial action. But the theory is surrounded with many 

 difficulties, and I am very anxious to see the question discussed by 

 others from the point of view which takes special account of the 

 condition of the disturbed subsoil. 



Mr. Tiddeman tells us that the period of the great ice-sheet " was 

 succeeded by a period of depression, well marked by marine sands 

 and gravels up to 600 or 700 feet in North Lancashire." Without 

 attributing such views to Mr. Tiddeman, I may ask whether it has 

 not been customary to argue from local deposits at high levels, to 

 general depressions of the land over larger areas than the observa- 

 tions warrant ? And still further, whether a distinction has been 

 preserved, as it ought to have been, between changes of relative 

 level, caused by elevation and depression of the land owing to in- 

 trinsic motions of the earth's crust, and changes in the depth of the 

 sea, such as might be due to the attraction of accumulations of ice, 

 or other causes disturbing the water-level ? The latter would clearly 

 alBfect larger areas than the former, though the variation of level 

 might often be less. And I felt this when in my paper on the warp 

 I described the last change preceding the recent period by saying, 

 " The sea was then depressed again, and the recent period com- 

 menced." ^ 



Mr. Tylor gives expression to a similar opinion in his late paper 

 on Denudation,- and tells us that there has been a great elevation of 

 the land "along a certain line; lifting marine beds 1200 feet at one 

 point. The movement was 350 feet in Lancashire, 200 feet at 

 Coalbrookdale, and thence gradually ceasing." He also remarks 

 that the Cyrena sands "in the Thames and Humber valleys reach 

 the same height within three or four feet, and are all under the fifty 

 feet range at the present time," and " a rise in the sea " of fifty feet 

 would immerse them. 



In fact, it seems to me that the strata of our island have long 

 oscillated at intervals, as if hinged about a line somewhere near the 

 eastern coast, and parallel to the general strike of the Mesozoic 

 rocks ; and that, in consequence, the more recent deposits are found 

 at a much greater altitude on the western side than their correlatives 

 occupy on the east. To the same cause I should attribute the tame 

 character of the scenery of the south-eastern district north of the 

 Weald. The Chalk and Oolites are not more easily denuded here 

 than elsewhere, yet the hills which they form are lower. The rocks 

 of Charnwood forest are sufficiently hard to form lofty hills; but they 

 do not rise more than 1000 feet, and rarely to that height. On the 

 other hand, atmospheric agencies are, and must always have been,. 



1 Geol. Journ., vol. xxii., p, 564. 



2 Geol. Mag., Vol. IX., p. 395. 



