Vol. 62.] THE CHALK AND BOULDER-CLAY NEAR ROTSTON. 491 



22. On the Relations of the Chalk and Boulder-Clay near Royston 

 (Hertfordshire). By Prof. T. Gr. Bonney, Sc.D., LL.D., 

 F.R.S., F.G.S. (Read March 21st, 1906.) 



In a paper read before the Geological Society in 1903, 1 Mr. H. B. 

 Woodward described three sections exhibited in pits on the Chalk- 

 uplands to the south of Royston, which in his opinion indicated that 

 a great ice-sheet, as it advanced from the north, had sheared off 

 large masses of Chalk and left them mixed up with its ground or 

 englacial moraine (the Chalky Boulder-Clay). I am aware that 

 authorities may be fdted in support of such an association ; but as I 

 have visited more than one alleged instance of it without becoming 

 a convert, and am doubtful whether any British ice-sheet ever 

 extended so far to the south, I venture to state why I am still uncon- 

 vinced. I carefully examined, in July 1904, the pit lying ' south- 

 west of JSFewsell's Park and north of Barkway ' : selecting this 

 because it evidently afforded the strongest support to Mr. 

 Woodward's view, and came away less than ever a believer. Last 

 October 1 returned thither in company with my friend, the Rev. E. 

 Hill, then but recently back from his third visit to Moen, in order 

 to have the benefit of his experienced eye ; and from this pit we 

 went on to that at ' Pinner's Cross, Smith's End, south of Barley.' 

 He took some photographs, which have been useful to me in 

 checking my diagrams; and I may add that, in all important respects, 

 he agrees with the views expressed in this paper. 2 



It will save time to state at the outset that 1 differ from Mr. 

 Woodward on questions of interpretation rather than of fact ; so I 

 shall refer the reader to his paper for a general description of the 

 details, and mention only those on which this interpretation depends. 

 But, before proceeding to them, I feel justified in offering some 

 objections of a more general character. 



Mr. Woodward and some other geologists apparently take it for 

 granted that an ice-sheet once occupied the English lowlands about 

 as far south as the Thames Valley ; or, in other words, that the 

 Boulder-Clay of that region is the direct product of land-ice. This, 

 however, as we must remember, is only an hypothesis. It may be 

 correct, but that has still to be proved. It involves grave diffi- 

 culties, and these have hitherto been met by explanations which 

 either are equally hypothetical, or, if true in themselves, are doubt- 

 fully applicable to the particular circumstances. To some of these I 

 shall presently refer in connexion with these sections, but think it 

 well to mention a very important one before proceeding further. The 



1 Published in the Quarterly Journal, vol. lix (1903) p. 362. 



2 I failed to find the pit 'north of Reed' on the former occasion, but have 

 seen it since this paper was read. As I expected, it proved nothing. [I went 

 again to the Pinner's- Cross pit last January, and to the Newsell's-Park pit also 

 in April, because at the former date quarrying was being clone which gave some 

 promise of discovering another fissure on the more northern side of the pit; 

 work had then ceased, without any definite results.] 



