462 Sir H. II Ho/corf/,— 



Lias Limestone at Croxton, 300 feet above its level, the steep 

 slopes of the Oolitic escarpment up which the ice must have 

 passed, the difficulties in the way of applying the prevalent land-ice 

 hypothesis become considerable." (Mem. S.W. Leicestershire, Sheet 

 70, pp. 82, 83.) I agree with every word of this, except the word 

 'considerable,' for which I should have substituted 'insurmountable.' 



Land-ice in any form, therefore, seems quite incompetent to 

 account for the Chalky Clay, nor can we invoke it without shutting 

 our eyes to innumerable difficulties which at, once arise. Some 

 geologists have therefore had recourse to floating-ice, in the form 

 of icebergs, or to coast-ice. This seems even a more desperate 

 appeal. It first necessitates our conceding a general submergence 

 of the country where the Boulder-clay is found, that is, as far as 

 the Thames in the south and Warwickshire in the west. Granting 

 this, how are we to solve by this agency any of the critical 

 difficulties of the Chalky Clay ; its existence in Lincolnshire to the 

 west only of the Wolds; its existence everywhere in great insular 

 areas separated from the sea; the complete absence of marine shells 

 or debris from every place where it has been examined ? How by 

 such means as icebergs or shore-ice can we explain the covering 

 of hundreds of miles of country with continuous blankets of 

 chalky clay, not deposited in local heaps and masses but in sheets 

 irrespective of the contour of the country, and in some cases 

 deposited in very deep beds indeed, and most conspicuously on the 

 higher grounds rather than the valleys ? How could such agencies 

 collect together oolitic blocks from Leicestershire and pieces of 

 hard chalk from Norfolk, and mix them with the Oxford or 

 Kimeridge Clays of the Fenland, or of the valley of the Ancholme, 

 and then spread them out, as we find them spread out, from Suffolk 

 in the east, into the Central Midlands? 



Mr. Skertchly has stated the case against icebergs with singular 

 force. " Icebergs," he says, " are the wrecks of land-ice, and the 

 rocky material they carry is derived from the gathering-grounds of 

 the parent ice ; hence, if the Boulder-clay be iceberg drift, its 

 components must be those of the distant gathering-grounds, and not 

 those of the rocks it falls upon as the berg melts away." He 

 goes on to say that as the chief ingredient in the clay is chalk, 

 as it is found 300 feet above the present sea-level, not only must 

 the gathering-ground have been on chalk but there must have 

 been a submergence of at least 500 feet. This would convert the 

 chalk area into a number of small islands, where it is not possible 

 to understand glaciers gathering at all. Again, all the argillaceous 

 matrix of the Chalky Clay is derived from the Fenland and the 

 valley of the River Ancholme, and all the formations whence it 

 could be derived would be under water. A more powerful 

 argument remains in the fact that, if the clay be of iceberg origin, 

 it can have no relation to the rocks on which it rests, except by 

 accident ; but the Chalky Clay does possess such a connection, and 

 the icebergs must have had a selective affinity in shedding their 

 burdens, by virtue of which they preferred to drop Kimeridge 



