The Chalky and other Clays of Eastern England. 461 



Moreover, according to any rational mechanical theory, how can 

 we account for the portage over wide areas of clay, scores of feet 

 thick, under an ice-foot at all ? How is it to seize it and move it 

 en masse in the way required? It would surely slip over itself at 

 once if the attempt were made to push it by means of a stupendously 

 weighted and heavy ice-foot. 



All these difficulties present themselves if we treat the glaciers as 

 ordinary glaciers, such as we know them, moving down an ordinary 

 set of hills, from the highlands to the lowlands. A fortiori do the 

 difficulties become intensified when the particular contour of the 

 country is considered. It must be remembered that the clayey 

 matrix of the great mass of these clays only exists in the lowest 

 hollows, where the denudation has been greatest. It is thence 

 that the Kimeridge and Oxford Clays must have come to form 

 the mass of the Chalky Clay, and been thence distributed in 

 various directions. It is in the low grounds of the Fen country 

 where the churning and mixing of the materials must have 

 been carried out, and it is thence the clay must afterwards have 

 been sporadically spread out and scattered. How are we by any 

 stretch of the imagination to realize an ice-sheet, formed in the 

 deep hollow of the Fenlands, collecting together from the four 

 winds of heaven materials for the clay, working and mixing them 

 up in the deepest part of the area where it occurs, and then 

 distributing it in various directions, always moving uphill from 

 the trough on to the plateau? The kind of reasoning involved is 

 assuredly going back to the dark ages of science, and getting away 

 from induction altogether. 



It does not seem possible to me that those who have postulated 

 these local glaciers have ever really measured or thought out the 

 conditions under which they would work at all. Mr. Jukes- 

 Browne has stated some of the insurmountable difficulties in an 

 excellent manner. Thus he says, writing of the Lincolnshire beds : — 

 "The Boulder-clay is not disposed in the manner of moraines, but 

 was clearly spread out as a universal mantle over the whole 

 surface of the country. The ice which produced it certainly could 

 not have been generated on the ridge itself, nor on any of the 

 neighbouring hill ridges, and yet the materials of which the clay 

 consists, and nearly all the stones it contains, are essentially local 

 products derived from the rocks in the immediate neighbourhood. 

 It is obvious that the chalk fragments must have been brought 

 from the north-east, the Carboniferous rocks can only have come 

 from the north or north-west, and the marlstone blocks travelled 

 in all probability from west or south-west of the places where they 



are now found When we consider the remarkable distribution 



of the stones and boulders in the clay of this area, the greater 

 proportion of chalk detritus on the eastern slopes, and of Jurassic 

 detritus on the western slopes, the fact that enormous masses of 

 marlstone occur many miles to the eastward of the only place 

 whence they can have been derived, the position of the large 

 boulder of Cornbrash, near Ingoldsby, and the occurrence of Lower 



