234 Notes on the London Clay and Bagshot Beds
waterworn—the re-sorted pebble-beds and glacial gravels
contain the Bagshot pebbles, with an admixture of angular
flints, quartzites, and other travelled stones. These remarks
will give a general idea of the relative position of the London
Clay and Bagshot Beds; and premising that there is no very
definite division between them, but that the clays gradually
become more and more sandy until they reach the lower
Bagshot Sand, which is described by Prestwich as consisting
of light yellow, fine siliceous sand, and which is now usually
recognised as the basement-bed of the Bagshots, and also
mentioning that these beds invariably lie conformably upon
the London Clay, I will describe the section at Oakhill
Quarry.
Section at Oakhill Quarry, Epping Forest.
The face of the quarry lies almost due east and west,
and I have noted some six or seven distinct beds, but
owing to the slips from the top and wash down the face,
it is exceedingly difficult to see all the beds clearly at one
time, although in dry weather most of them can be made out
pretty easily. When I measured it last Easter the total
depth of beds exposed was about 32 feet. The lowest (i,
fig. 2) consists of sandy, dark, black clay, changing in some
places to an olive-green ; thickness 12 feet, probably con-
siderably more, but the inferior bed was not exposed. At
Brentwood this bed is exposed to the depth of about 20 feet.
Upon its upper surface are found decayed Septaria. Fossil
remains are reported in this bed by the owner of the pits, but
I have not seen or found any specimens, with the exception
of a cast of shell enclosed in iron pyrites, which latter are
found rather abundantly. The next in order (h) is a mottled
grey, reddish, and fawn-coloured sandy clay, 3 feet in thick-
ness, somewhat similar to the mottled clays of the Reading