A SKETCH OF THE GEOLOGY
145
Herne Bay and Sheppey. They indicate a
climate decidedly warmer than the Essex of
to-day.
The London Clay extends far westward as
well as eastward of Epping Forest, underlying the
river deposits of the Lea
as well as those of the
Roding or the Crouch.
Within the area of the
Forest where it does not
form the surface it may
be met with at a depth
seldom exceeding 20 to
30 feet. Its uppermost
beds are usually loamy or
even sandy. They may
be seen in Oak Hill pit,
about a mile west of They-
don Bois Railway Station.
It is sometimes difficult
to distinguish between the
uppermost beds of the
London Clay and the
lowest of the Bagshot
series, which are next in
age.
The Bagshot Beds,
though they occupy a con-
siderable area around Bag-
shot Heath and Alder-
shot, form but little of the
surface of Essex, though
small, scattered, outlying
patches of them appear
at Rayleigh, near Brent-
wood, and between Epping
and Ongar. They consist of sand with partings
of clay. Within the present area of Epping
Forest there is but one small outlier, at High
Beach, a section in which was visible a few years
ago when the reservoir was being made. (See
Essex Naturalist, vol. i. p. 107.)
The London Clay and the Bagshot Beds both