IN THE GLACIAL DKPOJ^ITS AT HEN DON. 583 



raneous age with these undoubted Glacial deposits at Heiidon and 

 Finchk'V, which they so c4()sely roscmblo. This necessarily indicates 

 that mail lived in the neiiJ^libourhood of the Thames Valley at least 

 during a portion of the Glacial period, if not, as is highly probable, 

 in pre-Glacial times. 



PLATE XXir. 



Map sho»viug the Distribution oftbe Glacial Deposits in and arounl Hfiidoii. 



Discussion. 



^Ir. H. B, Woodward said the chief interest of the sections 

 related to the brown clay that occurred between the two hij-ers of 

 gravel. When he surveyed the Hendon outlier (in 1869) the lower 

 2:rave] was not ex])os-^d, and he took the brown clay to hd London 

 Clay. Dr. Hicks had clearly proved that this brown clay belonged 

 to the Glacial Drift. It could hardly be regarded as true Boulder- 

 clay, for although patches of gravel had been caught up in it, there 

 were no true erratic boulders, so far as he was aware, and the 

 '•' scratched stones " mentioned by Dr. Hicks afforded no convincing 

 evidence of glacial striae. The brown clay, however, behaved much 

 like Boulder-clay in the way in which it had here and there cut 

 abruptly into the beds below, and it might be regarded as a recon- 

 structed mass, a kind of boulder, in fact, of London Clay. The 

 "race" was a secondary product, due perhaps to the decomposition 

 of fragments of septaria derived from the London Clay. 



The features of the district, as Dr. Hicks maintained, were to a 

 large extent of pre-Glacial origin. He had come to this conclusion 

 while at work in Essex, where, as near Brentwood, the Glacial 

 Drifts smothered up some of the old features and abutted against 

 pre-existing outliers of Bagshot Beds. 



Mr. J. Allen Brown regarded the paper as of much importance 

 to those who, like himself, had been engaged in the investigation of 

 the Quaternary deposits in Middlesex. He pointed out the simi- 

 larity in many respects between the sections now shown and those 

 at " The Mount," Ealing, described and figured by him in the Pro- 

 ceedings of the Geologists' Association. In an excavation made 

 lately on Castlebar Hill, Ealing, of which he had made sections, as 

 yet unpublished, there was the same abrupt cutting off of the gravel 

 beds as shown in one of the present sections and the like infilling of 

 brown (probabl)'') Boulder-clay ; he considered that such brown re- 

 deposited London Clay was the equivalent of Boulder-clay, although 

 the boulders and chalky material were often absent. The matter 

 left by ice traversing a clayey cou-iitry would necessarily be chiefl}' 

 composed of clay, and what chalk might have been originally in it 

 would probably be dissolved out or redeposited as " race." There was 

 more clialky matter in such deposits the nearer the Boulder-clay was 

 found to the outcrop of the Chalk. He had seen chalk, sometimes in 

 large masses, with the stratified implemcntiferous gravels bent and 

 contorted between tliem, in the high-level drift-gravel near Langley 

 (Bucks), showing the passage of very large masses of ice during the 

 period when man was existing there. 



