TROCEEDINGB OF THE GEOLOGICAL SOCIETY. 3 



aliprniTiont with these ; and a sketch-section from Araharrow to 

 ]iarkham Hill shows the rcl.itive gradients of certain horizons to be 

 such as to justify the relegation of the pehble-bed there to the 

 base of the Upper Sands, owing to northerly dip on the north flank 

 of Finchampstead llidges ; while a microscopical examination of the 

 sands lends sup])ort to this conclusion. 



The mapping of the liagshot Beds as a pentad series (as worked 

 out in former papers) was shown in colours on the two sheets of 

 the six-inch Orduance-Survcj' Map, which include the Wokingham 

 and Wellington-College districts. 



A section was drawn from Wellington-College Well through the 

 sand-pit at the brick-yards by Ninemile Kide (8 ft. of the Middle 

 Clays exposed), Easthampstead-Church Hill (with more recent data), 

 and Bill Hill, to the South- Western Railway at Bracknell, bringing 

 apparently the higher beds of those two hills into the horizon of 

 the Upper Sands — recent excavations for building on the line of 

 section at rather more than a mile north of Wellington College 

 having demonstrated its accuracy for the critical portion of the 

 ground. 



In conclusion, the Author pointed out that the new well-sections 

 confirm the order of superposition at Wellington College as a vertical 

 datum-line ; he criticized the views of previous writers and main- 

 tained that, with the aid of Lieut. Lyons's recently published contour- 

 map, we can now discriminate between the effects of contempora- 

 neous and post-Eocene earth-movements in the area ; and that the 

 physical history of the Bagshot Beds, which he has propounded, 

 is further substantiated by the new stratigraphical evidence. 



Discussion. 



Mr. MoNCKTON believed the diagrams upon which the Author 

 rested his case were very incorrect, — thus the clays below the beds 

 of green sand in the Middle Bagshot do not extend to the north as 

 drawn, but crop out near the far signal-post north of Wellington- 

 College Station, and the well at the new cottages further north 

 passes through sands, and not through clays into sand, as shown in 

 the diagram ; moreover, the cuttings at the Ninemile Ride are in 

 yellow Lower-Bagshot sand, not in gravel. 



As to the hills from Bearwood to Ascot, the Author's contention 

 that they are Upper and Middle Bagshot fails, for there are excellent 

 and characteristic Lower-Bagshot sections all along the line, ex. 

 gr. : — Dowles-Farm sand-pit near Bearwood, 260 feet o.d. ; Tangley 

 railway-cutting,Wokingham ; Coppid-Beech-Lane road-cutting; sand- 

 pits at the top of the hill above Amen Corner, 275 feet o.d. ; and at 

 the top of Easthampstead-Church Hill, 280 feet o.d. ; also sections 

 at Bill Hill, Bracknell, and at the reservoir near Ascot Priory 

 on Goathurst Hill, 305 feet o.d. Signs of green sand were also to 

 be found at the tops of Bill Hill, Bracknell, and Burleigh, Ascot, 

 showing that Middh^ Bagshot once existed above these hills, which 

 could not therefore be Uj)per Bagshot. 



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