,344 G. W. Bulman — Glacial Geology. 



valley ; the few sections seen show plainly enough that masses of 

 sand and gravel pass into, and are interwoven with clay drifts in 

 such a way as to defy any attempt at separation over large areas, 

 although single sections may be indicated which do show a definite 

 sequence." 



An inspection of the remarkable series of sections from the 

 cuttings of the Settle and Carlisle Eailway given in Mr. Goodchild's 

 paper, showing the intimate interweaving of stratified sands and 

 gravels and laminated clays with till and boulder clay, indicate the 

 utter impossibility of referring the former to a distinct period. 



And it is interesting to note that, "towards the mouths of the 

 rivers, the total quantity of clay in the whole accumulation of drift 

 steadily decreases, until very little else than clean sand and gravel 

 is to be found, except in the maritime districts, where the true 

 boulder-clay comes on." For, as the ice descended the valley, the 

 greater would be the amount of aqueous action, and the less that 

 of ice proper. 



The glacial deposits of Lincolnshire, and the neighbouring parts, 

 may be cited as apparently favouring the view of interglacial epochs. 



Mr. Searles Wood (Q.J.G.S. vol. xxiv. p. 146) divided the series 

 as follows : — 



Hessle clay. 



Hessle sand and gravel. 



Purple clay. 



Sands and gravel. 



Basement clay (Chalky boulder clay). 



He maintained that there was a great break below the Hessle 

 beds, and separated these from the glacial series altogether. 



Supporters of the hypothesis of warm interglacial epochs will 

 find evidence for these in the intercalated gravels, and in the 

 supposed breaks in the series. 



For, the result of the survey of the district by Mr. Jukes-Browne, 

 leads him to place another break between the chalky boulder clay, 

 and the purple clay, although he repudiates the break higher up 

 established by Mr. Wood. 



A consideration of the facts brought forward by Mr. Jukes- 

 Browne (Q.J.G.S. vol. xli. p. 114), in his paper on the Boulder clay 

 of Lincolnshire, shows that the series of deposits — even if the 

 above division can be shown to be chronological — does not 

 necessarily indicate climatic changes. 



In the first place the chalky clay and the purple clay are not 

 found together in one district; the former occurs on the west of the 

 Wolds, and the latter on the east. 



" In East Lincolnshire," says Mr. Jukes-Browne, " there are only 

 three localities where the Brown Boulder-clay comes into contact 

 with the White Boulder-clay." And after describing these junctions, 

 he concludes that the appearances at these places are not against the 

 supposition that the brown clays pass into chalky clay. 



Other considerations, however — which do not appear to me con- 

 clusive — incline him to conclude that the two clays are separable 

 chrono ogically. But, whether this is so or not, the fact remains 



