194 MR. J. A. BROWiT ON THE THAMES- VALLEY 



discovered beneath 14 feet of brick-earth and gravel. Ifc is black, 

 but much abraded. 



On the southern shoulders of the Mount there is a deposit of 

 loamy sand and sandy clay surmounted by trail, the agglomerated 

 stones of which are often cemented by iron oxide into concretions ; 

 it is over 15 feet in thickness. This deposit reaches to the 130- 

 foot contour, and is divided from the glacial deposits above by a 

 band of London Clay. 



Prom the foregoing evidence, I am induced to believe that these 

 lower gravels were connected, until denudation severed them, with the 

 more beach-like deposits on the top of Castlebar Hill, if not also 

 with the " furrow " or Glacial gravels, &c. on " the Mount," and 

 that all are essentially parts of but one series of deposits. The 

 pebbly gravels at 155 to 160 feet above 0. D. must be very ancient, 

 so ancient, indeed, that they would appear to have been accumulated 

 when the physical geography of the country was altogether different 

 from what it is now. It would seem as if the northern tributaries 

 could not have been then eroded ; that very little, if any, of the 

 present conformation of the Thames Yalley had been fashioned ; and 

 that, so far as the present surface does coincide with that of this 

 olden time, it was submerged beneath those waters (possibly marine 

 or estuarine) which deposited this gravel upon ground just emerging 

 above the waves, which covered the Eocene area to the north, and 

 lapped the islands formed by the higher ground of Harrow, Horsing- 

 ton, and other hills. 



Although there is no positive evidence of any undisturbed land- 

 surface belonging to this early period upon which man may have 

 lived, it is possible that some of the most abraded implements in my 

 collection, the surfaces of which are almost destroyed, may have 

 been made at that time. 



The next series of beds in chronological succession present us 

 not only with man's handiwork, but with evidence that he lived in 

 the Thames Valley at successive levels up to the period when the 

 brick-earth series of loams, sands, and trail covered up and pre- 

 served the works of Palaeolithic man of the Drift. 



The variation in the thickness of the brick-earth series on the 

 high-terrace gravels is very remarkable ; the following is one striking 

 instance out of many : — On the line of the Avenue Eoad from 

 Castle Hill Station, where the gravel reaches to the surface, and 

 shows but small traces, if any, of brick-earth above it, northward to 

 St. Stephen's Church, the gradually deepening deposits of the latter 

 formation are very noticeable. Commencing at the Pyrmont Eoad, it 

 is found to be 6 feet thick at the Albany Eoad ; it increases to a 

 considerable extent at the Arlington Eoad, and deyelopes to a thick- 

 ness of over 21 feet near the Waldeck Eoad, with only about 2 feet 

 of gravel underlying it, making the whole thickness of the valley- 

 deposits at this spot (about 126 ft. above O.D.) 23 feet ; beyond this 

 it becomes shallower and thins out to the north, and is succeeded by 

 London Clay with the pot-holes of gravel I have described, connect- 

 in ^ the deposits with the thick beds I have mentioned near the 



