5b4 RECENTLY-EXPOSED SECTIONS IN GLACIAL DEPOSITS AT HENDON. 



He desired to know whether the Author had analysed the gravel 

 seen in these sections and whether he could distinguish any ditfer- 

 ence between the constituents of the higher bed and that at the base, 

 and what proportion of Southern Drift he found there, this being a 

 matter of considerable importance, now that Professor Prestwich's 

 valuable series of papers had appeared. With regard to the ana- 

 logous deposit on Oastlebar Hill, Ealing (about IGO O.D.), he had 

 found in it about 8 per cent, of ragstoue and chert pebbles ; 7 per 

 cent, of white (juartz, of which the largest was but little bigger 

 than a pea ; no northern rock but a small pebble of light quartzite ; 

 about 12 per cent, of black Tertiary pebbles, and the rest flint- 

 pebbles and subangular pieces of flint more or less stained, with 

 some blocks of sarsen-stone much eroded. 



Dr. G. J. HiNDE called attention to the fact that a notable pro- 

 portion of the fragments from the Hcndon Beds, exhibited by the 

 Author, consists of cherty rock, similar to that forming the Sponge- 

 beds of the Lower Greensand in Kent and Surrej', from 20 to 30 

 miles to the south of London ; and the mode of their occuirence in 

 their present position had not yet been explained. 



Mr. MoNCKTON remarked that the Glacial Gravels were very largely 

 composed of material derived from the near neighbourhood, and 

 this favoured the view that the valleys in which the gravels are 

 found were not previously formed, but were contemporaneous with the 

 formation of the gravels: that is, the portion of the valley in which the 

 gravels occur. In reference to Prof. Prestwich's suggestion (Quort. 

 Journ. Geol. Soc. vol, xlvi. (18f>0) p. 136) that the Hendon Gravels 

 might be Westleton, he considered that the presence of a large 

 proportion of subangular flints and the absence of any great quantity 

 of quartz-pebbles showed they were not Westleton but Glacial gravels. 

 He did not think that they were Southern Drift. 



The Author, in reply to Mr. Woodward, said he did not refej- to 

 the seams of cLiy as having been torn oft' from the floor by ice, but 

 to some distinct masses which were found enclosed in the Lower 

 Gravels. Replying to Mr. Monckton, he stated that when he said 

 that there was no barrier of any importance between Hendon and 

 the Thames Yalley, he meant no continuous hills like those of 

 Hampstead and Highgate. The Brent Yalley, which undoubtedly 

 had been scooped out before the Upper Boulder-clay was deposited 

 over the district, especially offered every facility for the extension 

 of the material in that direction. It was interesting to know that 

 ]N[r. Monckton and Dr. Hinde recognized a similarity between the 

 chert fragments and the chert of the Lower Greensand in the south; 

 but bethought it probable that similar beds must have been exposed 

 somewhere to the north, as about an equal proportion occurred in the 

 gravels underlying the Chalk}' Boulder-clay as far north as Whet- 

 stone. The Author was very glad to find that Mr. Allen Brown 

 had obtained further evidence to show that Glacial deposits occurred 

 near Ealing, and he had no doubt that ere long it would be possible 

 to show that they extended almost continuously from Hendon to 

 that area. 



