File:The Quarterly journal of the Geological Society of London (13071063503).jpg

1867..
DAWKINS LOWER BRICK-EARTHS.
97
of different circum stances of deposit, is observable. Its discrepancy
with the admirable section given in 1838 by Professor Morris may
be explained by the variability of the beds in the enormous pit.
The top of the Brick-earth is about 50 feet above the alluvium of the
Thames.
^. Erith. The second brick-pit is situated on the right-hand
side of the road from Erith to Crayford, immediately after it has
crossed the North Kent Railway, and about one mile from that at
Crayford. It is peculiarly interesting as affording a section from
the top of the Woolwich beds down to the Chalk, as weU as proving
that the Brick-earth rests on the edges of the Eocene strata, and in
a hollow excavated in the Chalk. In the diagram (fig. 4) I have not
attempted to give the horizontal distribution of the strata, but merely
the vertical thickness.
Fig. 4. — Section at Whitens Pit, Erith.
Vertical scale ^ in. to a foot. Horizontal extent not represented.
a. Chalk with flints, b. Thanet Sand, with a layer of tabular flints at the base.
c. Woolwich sand. d. Stiff black clay. e. Lenticular mass of shells.
/. Bed of black Eocene flints, with quartz pebbles, g. Surface-soil.
At the base both of the Eocene beds and of the Brick-earths lies the
Chalk with flints, nearly horizontal, and quarried to a depth of more
than 100 feet (a of section A). Above this is the Thanet Sand with
the usual layer of tabular flints- at its base (h of the same section),
and with a dip of 10° to the IS'.IN'.'W. It is overlain by the Woolwich
sand, reddish-brown in colour (c), containing a bed of stone, and in
its upper part consisting of sandy and loamy layers with Septaria
and many shells, on which rests conformably a stiff black clay with
few shells .d). Above this is a lenticular mass of Eocene shells,
very irregular (e), capped by a bed of black Eocene flints with
a few quartz pebbles (/), at the top of which is the surface-soil .g'),
a and e are peculiarly interesting as presenting the beds, in situ,
whence some of the materials of the " Trail " covering the Brick-earth
were derived.
At 50 paces to the south the gravel-series comes suddenly in, at
section B, where 14 feet of regularly stratified sandy gravel, com-