108 STUDIES, SCIENTIFIC AND SOCIAL chap. 



into the Baltic and North Seas, and also that which has 

 been carried away by rain and rivers since the ice age 

 passed away, and yet further, the enormous amount that 

 still remains on the lowlands of Scandinavia, and we shall 

 then arrive at an amount probably twice as great as the 

 above estimate, that is, something like five hundred feet 

 as the average amount of denudation of Scandinavia during 

 the glacial period.^ Now, unless this estimate is wildly 

 and extravagantly erroneous — and Professor Geikie adopts 

 it as, 'primd facie, not extravagant, we have an amount of 

 ice-erosion so enormous as to put completely out of court 

 all the allegations of those who attempt to minimise it as 

 a mere smoothing off of sharp angles and rugged surfaces. 

 I am not aware that Professor Bonney denies the Scandi- 

 navian origin of the greater part of the northern drift, and 

 unless he can show that its quantity is something like a 

 fiftieth part only of the estimate of Dr. Holland, I cannot 

 understand how he can still maintain that the glaciers and 

 ice-sheets of the ice age were agents of abrasion, not of 

 erosion, and that they were therefore impotent to grind 

 away the comparatively small amount of rock removed, 

 under the most favourable conditions, from the basins of 

 the valley-lakes whose origin we are discussing. 



Of course, it may be said that the bulk of the Scandi- 

 navian drift in Northern Europe is not a result of ice- 

 erosion, but of sub-aerial denudation, the product of which 

 was carried away by the ice-sheet. This may be admitted 

 as regards some portion of it, and especially of the heaps 

 of angular blocks previously referred to. There was also 

 probably a considerable layer of soil and of partially dis- 

 integrated rock in Scandinavia before the glacial epoch, 

 but both these elements will certainly not account for 

 more than a small portion of the drift, which consists 

 largely of boulder-clays, the undoubted product of glacial 

 erosion. This question has been carefully examined by 

 glacialists, and Professor James Geikie's conclusion is as 

 follows, referring specially to this northern drift : — 



"It is obviously impossible that the ground-moraines of an ice- 

 sheet of such dimensions could have been derived or even supple- 



1 Fragments of Earth Lore, by James Geikie, F.R.8. (1893), p. 167, 



