94 Hejjorts and Proceedings — Geological Society of London. 



slope with the higher and far narrower plateau of St. George's Hill, 

 having an elevation of 245 feet. 



For convenience of reference the portion of the section more 

 particularly described, and which has a length of 1070 yards, is 

 divided into four blocks : — 



Block A extends from Walton Station to where the unaltered 

 London Clay is seen — 313 yards. 



Block B extends from this to the point where the Bagshot beds 

 are first seen in situ — 345 yards. 



Block C extends from the above to the point where the Bagshots 

 are first cut through to the level of the line, and the hollow filled up 

 with Plateau-gravel — 165 yards. 



Block D exhibits the relations of the Bagshots to the Plateau- 

 gravel, where the latter is most fully developed — 247 yards. 



Details of Block A. — This portion of the section rises from zero to 

 12 or 14 feet; the first bed which becomes visible is the "Top 

 Sand," and on advancing further westward portions of a peculiar 

 mixture of gravel and lumps of brown clay form the sides and floor 

 of the cutting. This is evidently a disturbed series, and has peculiar 

 relations with a mass of yellow sand, mainly false-bedded, which is 

 70 yards long, and from 12 to 14 feet high at the west end. The 

 London Clay in situ rises very suddenly beyond this. Keasons were 

 given for supposing this sand to be a superficial deposit against a 

 steeply eroded surface of London Clay. 



Details of Block B. — The London Clay of this block has yielded 

 no fossils, nor are any Septaria visible. The bedding is difficult to 

 distinguish, but recent weathering has made it more plain. This 

 seems to establish a very slight dip towards the west. The surface 

 of the London Clay is undulating, and it is overlain by from 6 to 7 

 feet, of Plateau-gravel. 



Details of Block C. — In this block, where the cutting has a depth 

 of about 24 feet throughout, occurs the junction of the Lower Bag- 

 shots with the London Clay, and this is apparently an unconform- 

 able one. Both the lithology and the stratigraphy favour this view. 

 Nothing in the nature of a lithological passage exists. The lowest 

 bed of the Bagshots here is remarkably clear sand full of false- 

 bedding, and is succeeded by an argillaceous series, also somewhat 

 sandy. It was suggested that this latter might be the equivalent of 

 the " Ramsdell Clay." 



Details of Block D. — Here the Plateau-gravel attains its maxi- 

 mum thickness, since the Bagshots are cut through to the level of 

 the line in three places — depth of cutting from 24 to 27 feet, — thus 

 affording a fine opportunity for the study of this peculiar deposit. 

 Three horizons were roughly made out, or, rather, three varieties 

 occurring one above the other. Beyond the limits of the section there 

 is more distinct evidence of at least two groups in these Plateau- 

 gravels. No materials from the northern drifts are found. 



Other sections in the superficial beds were noticed, and more 

 especially one about the 180-feet line on the north slope of St. 

 George's Hill, where the contortions are of considerable interest. 



