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 Litter 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 15 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 talus from a cliff,