212 ON THE OCCURRENCE OF WESTLETON BEDS 



where no such mixing occurs, and where the one cannot easily be 

 mistaken for the other. Briefly, they may be described as being 

 made up of angular and rounded rocks, chiefly flint, and the angular 

 often in excess. Besides the flint, there is a motley collection of various 

 hard rocks — Quartz and Quartzite, Sandstone, &c., and some Volcanic 

 (Crystalline). The latter I have never found in Westleton Beds. 

 Prof. Prestwich's distinction of the Glacial Gravel is that of the 

 presence of dark brown ovate pebbles of quartzite out of Triassic 

 beds. This distinction I have not been able to apply, but it is 

 doubtless due to the narrowness of the field, or to imperfect 

 observation. 



We will now take the sections in detail : — 



From Bulford Station to Braintree Station, the line of rails 

 entirely rests upon Westleton shingle, the embankments filling up 

 the valleys near both stations being made up of Westleton rock 

 derived from Black Notley cutting, which lies intermediate between 

 the two. This cutting is from 20 to 30 feet deep, and the Westleton 

 Beds are, perhaps, of twice that thickness. I infer this from the 

 exposure of London Clay made on the other bank of the small river 

 flowing to the west of the cutting. It is capped with Boulder Clay, 

 which, as before stated, in all visible sections, is sharply divided from 

 the Westleton Beds, and has no intermediate member. The want of 

 this intermediate member (Middle Glacial Gravel) is apparent at 

 Braintree particularly, and more or less in the whole area under 

 observation. In fact, it is partly due to this that we have exposures 

 of Westleton at all. Most of them are made for gravel pits, and 

 these are not workable to a great depth. Therefore, if the upper 

 gravel be Glacial, and this much exceeds 1 5 feet, we have no know- 

 ledge of the underlying bed, as it is rarely pierced, except in the case 

 of wells, which we shall note later. 



At Braintree, the Westleton Beds have been very much disturbed 

 on the southern side of the town. The disturbance was most likely 

 due to river erosion in Post-glacial times, either leaving a cliff on 

 the side of the hill, or producing a landslip of some magnitude. 

 The facts are as follow : — In Hunnable's gravel pit, which lies on 

 the slope of the hill at about midway from its summit to the river 

 flat, Mr. Kenworthy obtained clearly-worked flint implements and 

 bones. These were overlaid by 15 feet of undisturbed shingle, 

 palpably Westleton, and this again by 5 feet of Brick-earth. The 

 explanation seems to be that they were covered by tahts from a cliff. 



