NOTE ON THE UPMINSTER BRICKYARD, 1890. 187
southward, and there is a passage downwards into current-bedded
sand and fine gravel, ranging in thickness from nothing to thirty
inches. This rests on an irregularly-eroded surface of gravel, sand
and loam, the bedding of which dips southward (in the opposite
direction to that of the upper beds just described).
The uppermost bed of this lower series is fine brown loam,
becoming more sandy downwards, and passing imperceptibly into
sheer sand, which in its turn passes down into well-bedded gravel
of medium coarseness. A thickness of three feet may be assigned
to the loam, and of one foot to the sand, whilst the gravel is seen to
six feet deep, and is not then bottomed. Owing to the southern dip
and the intermediate erosion, the base of the upper series touches in
turn each member of the lower, and at one point the two loams are
in contact, with pockets of gravel squeezed into the lower loam, and
contorting its lamination, the upper loam lying tranquilly over pockets
and contortions alike. Similar phenomena have been described in
these Thames-Valley Drifts as proving ice-action, but such is by no
means demonstrable ; for a small patch of gravel, laid down by a
freshet on soft ground, would sink by its own weight in course of
time, and the earth squeezed up out of place would moulder down
flat, or be melted away into the next flood, leaving a level surface
for future deposit. We do not need to enter the Arctic Circle to
learn how the Thames formed its gravels and loams.
The level of this patch of River Drift is high, being over 150 feet
above the sea, but it seems to be an isolated portion of the Up-
minster sheet, which is part of the high terrace of Romford and
Hainault. Possibly it is the deposit of a tributary from the north,
contemporary with, though a little higher than, the Thames gravel of
Romford, &c.
There are many problems yet awaiting solution in connection
with Essex geology, and amongst them the relations of the superficial
deposits call for extended observation on the part of residents in the
neighbourhood of sections in process of development, and the
details of which vary from time to time. The southern pit here
described shows points of which the ancient section north of the
lane afforded no trace, viz., a lower series of opposite dip ; and next
year, or this winter, some other new and important feature may be
revealed as work progresses, whilst the existing evidence may then
be destroyed.