J. Q. Goodchild — On Glacial Erosion. 361 



ice. But if the view here advanced be correct — that the ice removed 

 from the low ground all the weathered parts of the rock — it follows 

 that, because the stay of the ice at the higher points was brief as com- 

 pared with its stay lower down, much less of the high lying weathered 

 rock was removed ; and consequently, when the whole surface 

 became again exposed to the action of subaerial agencies, the sound 

 rock of the low grounds would be long in being affected, even where 

 it was not covered by drift, while at the higher points subaerial 

 denudation would soon remove the slightly glaciated surface and 

 replace it by another that would appear to have been always out of 

 the reach of the ice. Thus it is that in the Dale District the higher 

 lying rock surfaces show more decided traces of the action of the 

 weather than are to be found nearer the bottoms of the valleys. The 

 thorough glaciation of the low ground caused all the preglacially 

 weathered rock — swallow-holes, widened joints, and all — to be re- 

 moved ; whilst at higher levels even a considerable portion of the 

 preglacially weathered rock was left. In the one case the weather 

 has had to begin its work anew ; in the other it resumed work almost 

 where it ceased. The same remarks will of course apply equally to 

 those parts of Mid and Southern Eugland where the presence of 

 glacial drift marks the former extension of the ice-sheet. When 

 compared with its duration in the Northern parts of England, the stay 

 of the ice-sheet in the South was probably brief. Hence there would 

 be less modification of the rock surface than was effected where the 

 ice had a longer stay. Consequently, the slight amount of erosion 

 that the rocks underwent would favour the rapid replacement of an 

 ice-worn surface by one that to all appearance had been produced 

 solely by atmospheric causes. 



With regard to the quantity of rock removed from parts that had 

 long been exposed to glacial action, there does not seem anywhere 

 to be any satisfactory evidence. But when we reflect upon the 

 immense numbers of the boulders of almost every rock of marked 

 lithological character that have been dispersed far and wide from 

 outcrops of small extent, it is at once apparent that other rocks that, 

 as boulders, are not so easily followed, have, under a like amount of 

 glaciation, suffered denudation to as great an extent. The well- 

 known granite of Shap is a familiar instance. From a superficial 

 area of about a square mile and a half, lying just to the north of the 

 Lake District Watershed, and in such a position as to be long out of 

 reach of the ice, immense numbers of blocks have been dispersed in 

 an easterly direction from the Fell itself, over Stainmore, and far and 

 wide over the country to the East at least as far as the North Sea ; 

 while, owing to the southern overflow of this part of the Eden Valley 

 ice consequent upon the inflow from Scotland, great numbers of the 

 same boulders have been carried backward in the higher parts of the 

 ice, over the watershedding line, and away South by Lancaster, 

 Preston, and Chester, at least as far as the Vale of Gloucester. 

 What is true of any one rock therefore, must, under like circum- 

 stances, be equally true of those that it is associated with ; from this 

 it seems a fair inference that the quantity of rock removed from the 



