134 PKOF. J. PEESIWICU ON THE RELATION OF TFE 



largely of white quartz -pebbles. This gives a thickness at this spot 

 of 2d feet of Westletoii Beds ; but these sands and gravels extend 

 nearly to the top of the hill on which Braintree stands, and as the 

 well at the waterworks lower down shows that the base of the sands 

 is there 140 feet above O.D., while the summit of the hill is 

 above 234 feet, the Westleton Beds, round which the Glacial Beds 

 wrap, would seem to be here not less than from 70 to 80 feet 

 thick (see PL YII. fig. 1). 



It would appear from this and other instances to be named that 

 these Westleton Beds had a large development in Central and Nor- 

 thern Essex, but that that they have been extensively denuded by 

 the overlying Glacial drifts. The independence of the Westleton 

 Beds in respect to those of the Glacial Series here also becomes 

 more apparent, owing to the rise of the land and its waste before 

 the deposition of the Glacial Beds, in consequence of which the 

 latter, in the districts further to the west, where the rise was 

 greatest, gradually come to occupy a lower level than the former. 

 The separation of these two Drift-series, first clearly apparent in 

 this part of Essex, becomes more pronounced as we proceed west- 

 ward in the London Basin. The presence of Chalk and Jurassic 

 debris, with Quartzite pebbles derived from the New Eed Sand- 

 stone, readily serves to distinguish the Glacial from the Pre-Glacial 

 drifts. 



The Westleton Beds extend to the north-west, though but rarely 

 exposed, by Wethersfield to Duumow and Thaxted. In a pit just 

 south of the latter place is a section of some interest (fig. 10), as the 

 pebbly sands, which I take to be of Westleton age, and the overlying 

 Boulder-clay are both faulted. This, however, is from recollection. 

 I omitted at the time to note the constituent parts of the gravel. 

 The Survey officers consider it to belong to the Crag. 



Eig. lO.—Section near Thaxted (1850). 



o,. Pebbly soil. 



h. Whitish Boukler-clay. 



c. Coarse white sands with a few patches of gravel. 



c. Ferruginous sand. 



The Westleton Beds again showed in a pit at Braxted, 2 miles 

 S.W. of Thaxted, the section of which was as under : — 



1. Gravelly sancT and clay. 



2. White chalky Boulder-clay. 



3. Ochreous gravel, consisting essentially of flint- and quartz-pebbles, 



with very few subangular flints. 



4. Ochreous sand. 



