142 PROF. J. PEESTWICE ON THE RELATION OF THE 



The Berkshire Downs, which form the prolongation of the Chiltc] n 

 Hills of Buckinghamshire and Oxfordshire, rise above Streatly ard 

 Goring to the height of from 400 to 600 feet. In the line of the 

 Thames Yalley there is a broad high terrace of Glacial Drift, 

 ■whilst at a little distance further from the river the Westleton 

 Shingle appears on a relatively higher level. The Glacial gravel 

 forms a terrace at Southridge, and between Basildon and Ashamp- 

 stead, at a level of about 400 to 420 feet, whilst the Tertiary outlier 

 at Upper Basildon is capped by Westleton Shingle. The Tertiary 

 outlier (350 to 380 feet) north of Bradfield is also capped b}' a 

 gravel which may be of the same age. 



The Chalk Downs of Berkshire are much baier than those of 

 Oxfordshire and Buckinghamshire both of Tertiary outliers and of 

 Drift. The former are extremely scarce until we approach the 

 borders of the Tertiary basin near I^ew^bury. Nevertheless it is 

 probable that the Westleton Shingle extended over this area, for I 

 found on the bare Chalk-hills above East Compton a pocket of 

 Tertiary Sands and Drift, with flint- and quartz-pebbles, &c., — a 

 remnant probably preserved, like the Crag at Lenham, by the chance 

 circumstance of its being in a pipe or hollow in the Chalk. 



To the north and north-west of Newbury there are several 

 gravel-capped hills, possibly of this date, such as Donnington 

 Common and the hill east of Basford. One of the most prominent 

 is that at the end of the spur of Tertiaries which extends north- 

 westward from Newbury to AYickham. This hill, which is 560 feet 

 high and rises 100 feet above the surrounding Chalk-plain, consists 

 of Lower Tertiary strata (including the base of the London Clay) *, 

 and is capped by a bed of gravel, from 3 to 5 feet thick, composed of 

 flint-pebbles, with subangular flints imbedded in a quartzose sand 

 and grit very much worn. Prom its position and general cha- 

 racter I think it may be of AVestleton age, but I have no note of 

 its exact composition. 



The bare Chalk-plains of East Berkshire and Wiltshire offer scant 

 opportunities for determining the presence of the Westleton Shingle. 

 Except in a few rare instances denudation has swept these plains 

 clean of all but the superficial soil and trail. The higher Chalk- 

 hills near Baydon, 8 miles E.S.E. of Swindon, are, however, capped 

 by a gravel consisting of subangular flints and Tertiary flint- pebbles, 

 with some quartz-pebbles ; and a similar ridge to the east of Ogburn 

 St. George, on the north-east of Marlborough, is also capped by a 

 little flint-gravel with quartz-pebbles. 



Quartz-pebbles also occur in places in flint- drift on the hills about 

 2| miles south of Marlborough f. Patches of a pebbly drift again 

 occur on the higher points of the Chalk Downs at Bishopstone near 

 Shrivenham and at Liddington and Basdropto the south of Swindon, 

 but they are very indistinct. 



* Described in Quart. Joiirn. Geol. Soc. vol. x. p. SCy (1854). 



t The Dril't-bedd of this district have been described by Mr. T. Codrington, 

 iu the Magazine of the Wiltshire Archaeological and Isatural History Societj-, 

 1865. 



