File:The Quarterly journal of the Geological Society of London (13365640194).jpg

1850..
PRESTWICH ON THE LOWER TERTIARY STRATA.
263
Organic remains of stratum "c," at Maryland Point.
Cardium Plumsteadiense, Sow.
Cytherea obliqua, Desk.
Calyptrsea trochiformis, LamJc.
Fusus.
Melania inqninata, Defr.
Natica glaucinoides, Sow.
Ostrea Bellovacina, Lam.
Pectunculus brevirostris, Sow.
Pectunciilus Plumsteadiensis, Sow.
Pleurotoma, a small ribbed species.
Rostellaria Sowerbvi, Mant.
Tellina ?
Scalaria.
Teeth of Lainnse.
A boring MoUusk, probably a Litho-
domus.
It will be observed that this bed is here as well characterized as at
Clarendon Hill or Chinham, and that, with the exception of a single
specimen of the Melania inquinata, its fauna does not at all resemble
that of the Woolwich fluviatile beds. This solitary specimen had
also the appearance of having been rolled and worn.
The low country along which this bed outcrops from Stratford to
Horndon is covered with gravel and exhibits no sections. Some years
since, however, a group of shells, similar to the above, was found
at Stifford Bridge near Purfleet, and specimens of them are, I am in-
formed by Mr. Morris, now in the Geological Museum at Cambridge.
On the south side of the Thames, another outlier of the London
clay exists, I believe, on the Swanscombe Hills near Greenhithe, but
although I have examined them closely, I have not been able to meet
with a section of the basement beds.
We next arrive at the fine sections at Upnor on the banks of the
Medway two miles north of Rochester. We there have nearly all
the beds between the London clay and the chalk exposed in a few
large sections. For the present it will be sufficient to exhibit the
upper part of the section on the banks of the Medway, a short
distance beyond the Castle*. (See fig. 10.)
10. — Section at Upnor.
London clay ; upper part dark brown and very tenacious, pass-
ing down into sandy lighter coloured beds. No organic re-
mains have been yet found in it.
Brown clay and ochreous sand, with traces of lignite.
2. Light greenish sand, with a few patches of friable
shells. 3. Fine yellow sand, with a few shells. 4. In-
durated clay, with numerous shells and traces of
plants. 5. Yellow sand, the upper part full of round
flint pebbles, and the lower part abounding in shells.
Concreted masses, full of shells, not uncommon.
1. Light yellow and whitish sand ; upper surface indented
by stratum "c;" contains a few shells .Ostrea and
Cyrena) in irregular patches, and occasionally an un-
derlayer of large Ostrete. 2. A series of dark tough clays,
with subordinate lignite and beds full of the fluviatile
shells of Woolwich. 3. Variable yellow sands, reaching
probably to the chalk, at a depth of 50 or 6o feet below
"c."

• This section is described by Mr. Morris in the Proc. Geol. Soc. vol. ii. p. 451,