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THE ESSEX FIELD CLUB.
mammillated surfaces, and one of them measuring over 9ft. in length, attracted
considerable attention from the visitors. One or two fossils were found in the
Chalk, but time did not permit of a careful search.
Mr. Holmes' remarks are embodied in the following notes, kindly furnished
by him ;—
STRATIGRAPHICAL GEOLOGY OF THE GRAYS DISTRICT,
By T. V. HOLMES, F.G.S., F.Anth.Inst.
The Chalk, which is so prominent a formation on the Kentish shore about
Dartford and thence to Gravesend and Cliffe, is well exposed on the Essex side
of the Thames only between Purfleet and Grays Thurrock, though it appears
at Little Thurrock and East Tilbury, at the base of newer formations. Thence,
in Essex, it is not seen at the surface till we get to the north-west part of the
county, between Bishops Stortford and Saffron Walden. At Thames Haven,
about three miles north of Cliffe, the top of the Chalk is 268ft. beneath the
surface of the marsh there. It would seem that, in the Thames Valley hereabouts,
between Dartford and Purfleet westward and Cliffe and East Tilbury eastward,
the Chalk rises in a sort of low flattened dome. It is noticeable how very much
broader the windings of the Thames have been eastward of Cliffe and East
Tilbury (where they are no longer affected by the presence above the river-level
of that comparatively-hard rock, the Chalk) than they are between Gravesend
and Grays and East Tilbury. This is obvious from the unusual breadth of the
marshes between Cliffe and Pitsea.
Above the Chalk, in the great quarries at and near Grays, may often be
seen a few feet of Thanet Sand. This is frequently capped by sand and gravel,
deposited by the ancient Thames when it flowed at a higher level, and with a
more northerly course, than it now does. The great enlargements of the Grays
chalk pits which have taken place in recent years have often revealed the presence
of Greywethers or Sarsen stones in this old Thames gravel.1 As to the origin
of these Greywethers, Prof. Prestwick and Mr. W. Whitaker agree in thinking
that they are the hard remains of Tertiary beds, the softer parts of which have
been removed by sub-aerial denudation. Mr. Whitaker inclines to think that
these Greywethers have been largely derived from the Woolwich and Reading
beds and, in the western part of the London Basin, from the Bagshot Sands.
During the gradual changes in the position of the ancient Thames in this
locality, these blocks seem to have fallen gently from the bank to the bed of the
river, having come but a short distance from the spot at which they were
originally formed by concretionary action.
At five o'clock a move was made across the fields to "The Elms," where Mr.
and Mrs. Jonathan Seabrooke offered a most cordial welcome to the party, and
tea awaited us.
An Ordinary Meeting of the Club (the 281st) was then held, with Mr.
T. V. Holmes, F.G.S., Vice-President, in the chair. The Hon. Excursions
Secretary (in the absence of the Hon. Secretary) read the minutes of the
preceding meeting at Theydon Bois on 9th April, which were duly confirmed.
Mr. Percy Thompson remarked on the regrettable absence of the Hon.
Secretary by reason of ill-health, and suggested that a message of condolence
should be sent to Mr. W. Cole, and the hopes of the party for his speedy return
1 See paper by Mr. Holmes on these stones, as seen by him, in Essex Naturalist, vol xiii.
1904), p. 197.