92
THE ESSEX NATURALIST.
In all, seventy plants were noted in flower or in bud. Other
characteristic plants, not so advanced, were Lactuca Scariola, Foeniculum
vulgare, Dipsacus sylvestris and Blackstonia perfoliata.
The birds observed included the following:—Willow Warbler, White-
throat, Nightingale, Chaffinch, Yellowhammer, Wren, Greenfinch, Skylark,
Song Thrush, Blackbird, Great Tit, Swallow. Swift, Turtle Dove, Jack-
daw, etc. A Common Lizard was seen basking in the warm sun, but
easily evaded capture.
The markedly yellow tint of the water in the settling tanks, in which
whiting is prepared, attracted attention: Mr. Scourfield reports that
microscopic examination showed the presence in the water of no organisms
in sufficient numbers to explain this colouration.
After lunch, the visitors (with the exception of a few cautious indivi-
duals) climbed the highly-inclined talus-slope of sand up to the level of
the upper pit, where Thanet Sand, overlain by Pleistocene Valley Gravel
(the "Boyn Terrace" of the Thames Valley Deposits), is worked above
the Chalk. The Honorary Secretary gave an informal account of the
geological features of the quarry, and called attention to the large grey-
wethers or sarsens lying on the floor of the upper pit: one of these is over
nine feet in length and all present beautifully mammilated upper and lower
surfaces. Several smaller greywethers were noticed in situ in the over-
lying Valley Gravel, These sarsens are masses of locally indurated sand
due to cementation by a siliceous cement, and come from some loose
sandy bed (probably of the Woolwich and Reading Series) which has
otherwise been denuded away. The possibility of ice-action being con-
cerned in their transport for some short horizontal distance was touched
upon and in this connection the occurrence of festooning ("trail") in
the top Gravel was called attention to.
A circular, saucer-shaped hollow, some thirty or more feet across,
in the exposed surface of the Chalk, from which the overlying beds had
been quarried away, was commented on, and the probability of its marking
the position of a collapsed Denehole was mentioned, it being on record
that deneholes have been come across during the quarrying operations
in this quarry.
An attempt by some of the more adventurous of the party to proceed
along the narrow western ledge left between the Chalk and the Thanet
Sand had to be abandoned as too dangerous in places.
After being photographed near the entrance, the visitors left the
quarries shortly before 4 o'clock and repaired to the Queen's Hotel, in
the town, where an excellent tea was served. Afterwards, a very pleasant
hour was spent in rambling through the older part of the town, visiting
the largely rebuilt parish church, and watching, seated on the "promenade
facing the Thames, the wonderful changing effects of light upon the water
as sun and heavy clouds alternated, and the procession of great steam-
ships, outward bound, dropping down the river with the tide.
The 6.26 o'clock return train to London brought to an end a delightful
day's excursion, unmarred by the few showers which diversified the day.