GEOLOGICAL NOTES IN THE NEIGHBOURHOOD OF ONGAR. 91
2. Gravel roughly stratified, composed of flint pebbles and
subangular flints with some large unworn flints, many
small quartz pebbles and a few pieces of large quartz,
one three inches in longest diameter, also a little
chert and ironstone.
Gravel pit close to Greensted Church. 219 feet O.D.12
1. At one place there is a patch of red clay 11/2 feet thick,
and at another 2 feet of grey clay. Boulder Clay.
2. Well stratified gravel, 6 feet seen. Glacial Gravel.
The gravel is composed of flint pebbles, subangular flints, a little
quartz, some fragments of ironstone and chert. I could not find
quartzites or quartz blocks, or other glacial erratics.
Pit in field 3 furlongs north-west of Greensted Church,
near Old Barn, 240 feet O.D.
Gravel, 4 feet, very like the Westleton Shingle of Cooper-
sale Common at first sight, being of a greyish-
white colour, very clayey.
Composed as follows:
Flint pebbles, very large proportion, many three, some four
inches in length.
Subangular flints, several in situ, low down in the section,
and on the heaps.
Quartz, very little, largest pebble one inch long.
I could find no glacial erratics.
The gravel at Greensted differs from that described at Laver,
Moreton and Shelly Bridge in the greater abundance of flint
pebbles, and in the scarcity, or perhaps absence, of erratics. The
reason, no doubt, is that it is mainly derived from the Pre-Glacial
pebble gravels of the neighbourhood; indeed, if, as I suspect, the
Roding Valley had been partially excavated before the Boulder Clay
period, it is quite possible that some of the Greensted gravel may
be pre-glacial.
Gravel Pit west of the Lake in Navestock Park, about
140 ft. O.D. Whitaker, op. cit., p. 314 ; Mr. Wood-
ward's notes. Gravel, seven feet of a yellow colour
with some colourless patches, coarse sand in places,
roughly stratified and in one place contorted. The
gravel is composed of flint pebbles and subangular
flints in about equal proportion, quartz pebbles up
to half an inch in length occur.
I did not find erratics here, but further search is required. I
12 See Whitaker, op. cit., p. 314.—Professor Dawkins' notes.