A SKETCH OF THE GEOLOGY
While at Coopersale Common or Gaynes Park he
states it to be :—
Small patches of this gravel may be seen at
Earl's Path (the road from Loughton to High
Beach), and also along the road between the
Robin Hood Inn and the Wake Arms. Though,
as before remarked, of much later date than the
Bagshot Beds, the Westleton Shingle, though post-
Pliocene, is yet pre-Glacial in age. Prestwich
notes, inter alia, that it contains pebbles of southern
origin unknown in Glacial Deposits.
The beds belonging to the Glacial Period con-
sist, in this district, of sand and gravel underlying
boulder clay. The sand and gravel varies very
much in composition and in general character and
aspect, while the Boulder Clay, commonly known
as the " Chalky Boulder Clay," from the numerous
pebbles of chalk it contains, is singularly invari-
able in appearance, whether seen in Norfolk,
Suffolk, Essex, or Hertfordshire. In composition
the Glacial Gravel consist chiefly of flint, sub-
angular or rounded; quartz and quartzite, flint
greatly predominating. Sometimes rolled fossils
from the Lias and Oolite have been found in it.
The Chalky Boulder Clay is easily identified
wherever there is a section having a depth of 5
or 6 feet or more. But it often happens that the
foot or two next the surface is so much altered
by the dissolving away of the chalk pebbles and
other calcareous matter through the agency of
rain-water, as to be scarcely recognisable.
Patches of gravel of considerable size, with no
covering of Boulder Clay, but which seem on
general grounds to be, in all probability, of Glacial