The Essex Naturalist
121
The natural history of the Thames Terraces at West Tilbury
R G Payne1 &PR Harvey2
1Southend Central Museum, Victoria Avenue, Southend-on-Sea, Essex
29 Kent Road, Grays, Essex RM17 6DE
Near the small village of West Tilbury (grid reference TQ6677) there is a ridge
of hills which form part of the Thames Terraces. As one might expect, lying on
old Thames gravels, they are composed of very well-drained, sandy soil.
Although they have been exploited extensively for sand and gravel extraction,
and the area is intensively farmed, there are still a few remnants of ancient
unimproved pasture. Several of these areas have been studied by the authors
since August 1991 and have proved to be extremely rich both in plants and
invertebrates.
Because the ridge runs east-west, there are south and south-west facing slopes.
The sandy soil, often exposed by rabbits, provides excellent breeding sites for
many scarce invertebrates, particularly aculeate Hymenoptera (bees, wasps and
ants). On the summit of Broom Hill (TQ6577) there is an old, fairly shallow
quarry with sandy exposures. This has proved to be a particularly rich habitat for
Hymenoptera especially where the low cliffs face south. A large number of
nationally scarce species have been recorded.
The slopes of Broom Hill are grazed by a small number of horses and a large
population of rabbits. Scrub clearance, mainly of broom and hawthorn, has been
carried out (1993), and attempts have been made to thin out Ragwort plants by
pulling them in late summer (1992).
On Broom Hill and probably on other areas on the ridge, there was almost
certainly some woodland at one time. Bluebells are common over much of
Broom Hill, growing well out in the open in short turf - an unusual sight in
Essex. On the southern slope of this hill there are a number of old elm stumps,
slowly rotting away, providing a small, but important niche for some
invertebrates, such as the tenebrionid beetle Helops caeruleus.
Many of the plant species, however, indicate that these pastures have
remained open grassland, probably grazed by rabbits for a very long time. Herein
lies the hill's value. This type of habitat, unaltered for centuries is now very rare
with a uniquely rich assemblage of plants and invertebrates. It is a remnant, a
tiny relic, of what must once have been a common habitat along the hills of the
Thames Valley. These hills once sloped down to Tilbury Marshes, now drained
and used for arable farming. Even now the marshland drainage ditches are home
to Hottonia palustris (Water Violet), Groenlandia densa (Opposite-leaved
Pondweed) in its last Essex haunt and Rumex hydrolapathum (Great Water
Dock). Great Green Bush-cricket Tettigonia viridissima colonies are found
amongst the reeds on the marshes and also amongst scrub on the hillside. There
is even an old record of the Field Cricket Gratis campestris from the Tilbury