Vol. 62.] CHALK AND BOTJLDEE-CLAY NEAR ROYSTON. 497 



even if Boulder-Clay can be proved to be the product of an ice-sheet, 

 and the latter to be capable of shearing off and disturbing large 

 masses of Chalk, these sections, so far from being explicable by that 

 process, are quite the contrary. 



Discussion. 



Mr. H. B. Woodward said that he was pleased to learn that the 

 Author found no serious fault with his facts ; they appeared to 

 differ, however, with regard to the amount of mechanical distur- 

 bance visible in the pit at Pinner's Cross. He remarked that the 

 chalk-pebbles which characterize the Boulder-Clay might well have 

 been derived from a land-surface of Chalk, as the Chalk weathers 

 into a rubble of rounded fragments. He admitted that his ex- 

 planation of the disturbances depended upon a belief in the land- 

 origin of the Chalky Boulder-Clay. To that belief he had been 

 wedded for many years. The mode of origin was supported by the 

 general uniformity and character of the Boulder-Clay over wide 

 areas in East Anglia and the Midland counties, varied as its com- 

 position was by local ingredients from the formations over which 

 the ice moved. It was indicated also by the frequently-disturbed 

 state of the subjacent strata. He referred to a noteworthy proof 

 of the land -origin observed in cuttings of the Great Central 

 Railway. 1 



Prof. Boyd Dawkins said that the point laid before the Meeting- 

 seemed to be rather a matter of opinion than of facts. The 

 Author might be right in this case, but the effects of the pressure 

 of ice on the surface of this country were undoubted. There had 

 been no movement of ice from the low to the high ground, but 

 there had been from the high to the low. The crumpling shown 

 here was not due to anything that took place on land, but icebergs 

 impelled by wind and waves would delve up the shore on which 

 they stranded. 



The evidence as to the physical configuration of the district was 

 of great interest, the difference between the gentle slope of the 

 Chalk in the Cambridgeshire area and on the borders of Essex, and 

 the steep scarps of the North and South Downs, being doubtless 

 due to Glacial phenomena. 



The Rev. Edwin Hill said that he agreed with the Author's 

 views. He had thought that Mr. AVoodward's paper had built high 

 on a small foundation. It attributed to ice-sheet thrust a roll in the 

 Chalk, on account of some included clay, and that clay, on account 

 of the roll in the Chalk : then, on these as foundation, built an 

 ice-sheet. 



Mr. Lampltjgh remarked upon the Author's objection to the 

 land-ice hypothesis, and suggested that, if the evidence for this 

 hypothesis in Eastern Britain was considered in its entirety, the 

 Author's difficulties in accepting Mr. Woodward's interpretation of 

 the Royston sections would* vanish. As in every other result 

 attained in geology, it was quite possible to pick out points difficult. 



1 See Geol. Mag. 1897, p. 103. 



