6 The Essex Naturalist Natural history As far as natural history goes, I fear that more has been lost than has survived. The marshes were drained quite early but remained as grazing marsh until fairly recently and small areas near Tilbury Fort and the power station still survive. Once they would have been grazed by cattle and sheep, now horses are more prevalent. Much of the marshes and the higher land is now arable. Old photographs show the area to have had more trees than now. These would have been elms before the (inset of Dutch Elm disease. Many great stumps can still be seen and there is an abundance of elm suckers in the hedgerows. Huge quarries, later filled with London's household rubbish which arrives in convoys of trucks and by barge, scar the landscape. These were later landscaped, but the result is a totally different scene to what existed before. Much of the marshes east of Tilbury Power Station ate covered by a deep layer of fly-ash, the by-product of coal combustion. Only in a few places has the rich flora and fauna of this ravaged countryside survived. There are a few small areas of Saltmarsh and remnants of the once extensive grazing marshes. The old drainage ditches are still there, but many now criss-cross ploughed fields where unfortunately the marginal vegetation is cut and they are periodically dredged. Run-off from agricultural fertilisers and other chemicals must also adversely affect them. Of the pastures on gravel terrace hills, there are still one or two remarkable survivors which I shall come to later. The Mar Dyke is still there but Bulphan Fen has long been drained. Orsett Heath is a golf course, but on its fringes many rare species still hang on. Despite all these drastic changes, nature is resilient and quick to make use of opportunities. Abandoned quarries have quickly been colonised by plants and invertebrates from surviving natural areas. Even the fly-ash east of Tilbury Power Station has been colonised by several interesting plants and insects. This is not a neat and tidy landscape. Few stockbrokers would consider living here; fences fall down, there is fly-tipping, abandoned cats, graffiti and small holdings. Perhaps it is this air of general neglect and untidiness that has helped a lot of the wildlife to survive until the present time. Parts of the Tilbury area have been known by botanists for many years. There are lists in Gibson (1862) for Tilbury Fort and the coastal areas have long been visited by bird-watchers. The Thurrock Natural History Society has been active in the area since 1970 and in 1980 published a useful summary of some of the more interesting sites in the area. Nevertheless, it has emerged in the last few years that a great deal has been overlooked especially as far as the invertebrates are concerned. Until recently the area held one of Britain's rarest plants, the Hartwort Tordylium maximum which survived into the 1980s along Fort Road near Tilbury Fort. It was first found there in 1875 but was destroyed by pipe- laying in the 1980s. The plant now only survives on Hadleigh Downs in one small area. White Horehound Marrubium vulgare was recorded in Gibson from