80
NOTES ON GEOLOGICAL RAMBLES
two brick-earths ; they have been formed under like conditions, and
from the same sources of materials.
The railway cutting opposite affords fine exposures of the Glacial
gravels,1 overlaid by the Boulder Clay. In the latter, highly fossili-
ferous blocks of Oolitic rocks from the Midlands are not unfre-
quently found. The underlying sands and gravel are often cemented
by iron into a hard stone, as at Black Notley, Panfield, &c. Blocks
of this consolidated material form part of most of the churches, &c.,
in the district.
Our member, Dr. J. Taylor, of Bocking, has a singular chalybeate
water supply from the artesian well of which Mr. Whitaker gave us
the section last year.2
The water contains much carbonate of iron and carbonate of
lime, and both are thrown down, on standing, as a heavy ochreous
precipitate. In the kettle, the precipitate, instead of forming a
coherent fur, comes down in the form of independent nodular
grains, strikingly resembling those of Oolitic limestone.
Under the guidance of Mr. French, of Felstead, we re-
investigated the interesting deposits which he has described in the
Essex Naturalist (vol. iii., pp. 11-15) as occurring in that
part of the Chelmer valley, and consisting of peat and marl
draping the slopes of the main and lateral valleys. They contain
abundant remains of land-shells, some of species no longer frequent,
if not absolutely extinct in the neighbourhood. As thus forming a
record of changes of fauna these deposits are of high interest,
although, being produced by chemical rather than mechanical pro-
cesses, they find no place in the British Stratigraphical series, not
being stratified like the alluvium, with which, chronologically, they
are equivalent. The slopes which these deposits drape consist of
London Clay, Middle Glacial gravels, and Boulder Clay, the gravels
being very irregular in their mode of occurrence.
On Glandfields Farm, below Causeway End, a mile southward
of Felstead, was seen a small patch of true Post-glacial material,—
sand, gravel and loam,—resting on the flank of the hill about the junc-
tion of the London Clay and Boulder Clay, and of parallel age to the
Braintree brick-earth mentioned above, being at about the same
height above the present river-bed. Some bones from this deposit,
apparently those of deer, will shortly be submitted to the British
1 Prof. Prestwich, in the latest number of the "Quarterly Journal of the Geological Society"
classes part of these gravels as Westleton Beds (V pre-Glacial). See Q J. G. S., vol. xlvi, p. 133.
2 Essex Naturalist, vol. iii, p. 45.