Inholms clay pit: The North Holmwood local nature reserve In September 2008 Holmwood church held a fair, at which Surrey Wildlife Trust had a stall about our local nature reserve, the Inholms Clay Pit. While I was manning this stall, a number of people came along who lived on the estate but had no idea that there was a nature reserve literally next door. By contrast, one man (Brian Chandler) also came along who turned out to know far more about the site history than I did, since he used to work in the brickworks long before the clay pit was excavated. Subsequently Mr Barker (of Inholms farm, whose family owned the land and who still owns land east and west of the site) corrected a draft text with regards to local history. I am indebted to both men for this help. This article is an attempt to crystallise these experiences, to advertise our local reserve and to record its history for posterity. First things first: Inholms Lane Clay Pit LNR (local nature reserve) is open to all at all times; all you have to do is walk (south) along Holmbury drive (in the middle of the North Holmwood estate) to its end, where a short path leads to a large concrete tunnel under Inholms lane. A few people find this entrance slightly intimidating, but don't worry; you are totally free to explore. Once through the tunnel there is a sudden, remarkable transformation, from a dark industrial concrete underpass to a light, welcoming open space with a wide path, seating, and an interpretation board about the site. The main path now leads along to the west, up to a viewpoint where you can look down on the Surrey landscape and see nothing but countryside as far as Reigate Hill. Bring binoculars to see whether you can see any windmills near Reigate! Inside the reserve you find yourself walking along the bottom of a south-facing bowl. This sunny aspect makes the site a haven for many insects, notably butterflies, while its fringing woodland supports various birds including woodpeckers, bullfinches and warblers. You can often see buzzards (or hear their cat-like mewing calls). These are best seen from the viewpoint, looking east over the fields towards Reigate. Other raptors include sparrowhawk and kestrel, plus less frequent sightings of peregrines and goshawk. On your return from the viewpoint you may want to explore the birch/willow carr woodland that covers much of the eastern half of the site: listen for parties of tits, look for mushrooms in the autumn and marsh orchids in early summer. The site is not large, roughly 500m long by 100m wide, but has a remarkable range of habitats and many little paths to explore. The site is owned by Mole Valley Council on a 999 year lease (now more like 990 years, having started in the year 2000), but is managed by Surrey Wildlife Trust who coppice the wlllows, mow the boggy areas and supply benching etc. Having explored the site, you may want to know more about its history. The site owes its existence to the activities of Dorking Brickworks, which closed in 1981 but operated from what is now the North Holmwood estate for about 60 years from the 1920s. I am deeply indebted to Brian Chandler (of Chart Downs) for his recollections and photographs of these works, which proved to be more illuminating than anything in the council / SWT archives. Brian started working in the brickworks in the 1930s, following his father, and was initially employed to move bricks at a rate of 3d (= 3 old pence or 1.25 new pence) for 1000 bricks! Dorking brickworks was one of the major local employers for several generations, and relied on the high quality weald clay that abounds in the Holmwoods. You needed an equal mix of yellow clay, brown clay and blue clay, which were mixed by machine, formed into shape in moulds then baked in coal-fired ovens. (Hand made bricks were more expensive, and had a different surface texture). This clay was cut from the land around the works: Brian has a photograph showing a cliff about 5m (c18 feet) deep being cut away, roughly where Holmwood drive now stands. This is the height difference between the North Holmwood estate and Inholms lane, which was once just a normal country lane but now stands proud like a hogsback. The woodland that now cloaks each side of Inholms lane is therefore quite young, despite appearances. The main area of clay, north of Inholms lane, was effectively dug out by the late 1950s, leaving the brick works (then owned by Redlands) with the options of expanding south of Inholms lane, or closure. Accordingly the clay was dug out from south of Inholms lane. Exactly when this started is a little vague; one date quoted was 1961, but I have met someone whose brother worked south of Inholms lane around 1955. Each time that one walks into the clay pit this industrial legacy remains manifest in the solidly functional concrete tunnel under Inholms lane, through which clay was once dragged. (Fragments of heavy, rusted iron cable still sometimes turn up on site, used to drag the clay buckets along). The transfer of land was contentious. From the late 1950s onwards Redlands took land from Inholms farm in stages, with an agreement to return the land to agriculture after excavations had finished. Once completed however, Redlands instead arranged to transfer the land to the council, initially without the farmer's knowledge, and against his subsequent protest. The digging started by the underpass, then expanded westwards. This created the claypit reserve as it now stands, and gives the site a gradient of age from oldest (c. 1960, by the underpass) to youngest (1988, the far western slope, leading up to the viewpoint). This age mismatch is still easy to see in the contrast between woodland and semi-bare clay, but will decline as the site matures. It seems that the useful clay here was more limited than expected (too little brown clay), and the site ran out of capacity in 1988, leading shortly thereafter to the closure of the brickworks and the subsequent building of the North Holmwood estate. Brian has a photograph (taken looking north through the Inholms lane tunnel) taken Xmas day 1988 showing the start of building work on the new estate. It is a fascinating and unresolved exercise to attempt to reconstruct the floral history of the site. Brian Chandler was not involved in the planting/seeding of the site, and I would dearly love to meet anyone who can tell me about its management history up to the 1980s The National Trust have an aerial photograph of the Holmwoods (sadly undated) showing the clay pit as all green but without the birch/willow scrub that now dominates the east of the site: this was presumably taken in the early 1990s. By 1999 (when the site was properly surveyed) dense scrub woodland was developing on much of the site, and scrub control has been a recurring site theme ever since. Left alone, the whole site would become tall dense birch/willow scrub within a few years: the grassland is maintained by winter mowing by a contractor. It is important to understand that, in this case, leaving the site entirely "to nature" would result in fewer species than we currently enjoy, because for diversity of species you need a diversity of habitats. The most distinctive flowers of the site can be seen in the grassland in June/July: the purple spikes of marsh orchids, growing among the yellow flowers of lesser fleabane. Look carefully - each orchid has different patterns on their flowers, all complex and lovely, despite being the same species (Dactylorhiza fuchsii). In 2008 a second orchid appeared, the southern marsh orchid, but only a single plant, so don't expect to see it unless you look hard! About half the plant species on site need full sun, and will die out if shaded. Because of this, one of the main management activities is clearance of birch/willow scrub, usually followed by burning it. This conservation activity should not be equated with people using our woods for their BBQs! Although apparently hypocritical, this is because informal bonfires tend to leave litter and to chop down the wrong things. (There are hectares of willow that I'd love someone to chop down and burn, but in summer 2008 when someone cleared an area, made a house and a BBQ pit they ignored all the mundane willow and selectively logged our best ash glade!) There is one habitat that I would love to claim for the site, but of which only a faint residue remains, namely ancient woodland. This has a formal definition, namely woodland present in AD 1600 (and as far as can be told thence continuously back to the ice age). This is most easily spotted by the presence of slow-colonising but persistent plants, of which native bluebells are a good example. Bluebells tend to get moved around by gardeners (especially the non-native Spanish bluebell), but there are other plants with similar behaviour: collectively these are known as Ancient Woodland Indicators. The woods in the clay pit have 4 good indicators: bluebells, primrose, dogs mercury and wood anemone. So are they ancient? No, Brian has a 1950s photo of the Inholms lane area clearly showing a cereal field where the claypit now is, with no woodland in sight. (To be technical there were several cereal/arable fields on this land, going back at least as far back as 1643). So the woodland is assuredly not ancient, so what are the indicators doing here? There must have been tiny thin slivers of land remaining, holding the ghost of an ancient woodland plant community. What I am calling a woodland fragment is what land owners call a hedge. These plants hung on in the hedgerows, and indeed may still be seen in hedges elsewhere along Inholms lane. A few patches of bluebells, primroses, Mercurialis, and exactly 4 clumps of wood anemone, hung on for at least 350 years in the hedges bounding the clay-pit-to-be. (Only the northern and southern boundaries, showing these hedges to be older than the eastern and western ones). When the field was taken over by Redland and arable field turned to woodland, these woodland plants did exactly what they have always done - moved sideways into new suitable habitat. The primroses have spread furthest, with a really good display to the left of the entrance in April, and plants having moved c. 10m into the flat lagoon bottom from the closest slope. The Mercurialis is widespread in the boundaries of the site, but is always rather a drab plant. Our 2 best ancient woodland indicators are bluebells and anemones which hang on only in the boundary strips, especially along Inholms lane. I have a long term plan to extend the distribution of these 2 plants along Inholms lane, but always only in the roadside edge (mimicking a hedge refuge, and incidentally benefiting passing motorists!). Over the years these attractive plants will creep inwards, and eventually creep down the south-facing slopes of the claypit. The rate quoted in conservation literature is 1m a decade, but if that is so our plants must have had a 20 year lag because few have spread even 2m from the old hedgeline. They will speed up once on the slope (where seeds roll down), but even so we should not expect to see the clay pit woods full of bluebells for at least another 200 years. Yes, we could just introduce them by hand and it would look lovely, but would be closer to gardening than reserve management because it would be working against the site history, obscuring instead of highlighting the waves of floral colonisation moving into the site. The clay pit was designated LNR status more for its invertebrates than its flowers, notably its butterflies. It was (briefly) the only colony of the small blue butterfly off the chalk, though these vanished with their foodplant (kidney vetch) around 2000. In summer you are sure to see meadow browns flitting around the flower heads, often with skippers, common blues and marbled whites. Other notable invertebrates include the cone headed bush cricket and several solitary bees. (One, Eucera longicornis, can be recognised by eye as being a small bee with ridiculously enormous antennae). It was to benefit insects that in November 2007 a south-facing cliff was dug. This was certainly used by at least 4 sorts of hymenoptera (bees and wasps) in 2008, although we do not have definite names for these yet. The cliff is also important for jumping spiders, as well as showing the local soil profile nicely. These species are all solitary, harmless, non-stinging forms - there is absolutely no danger in inspecting the cliff, though I'd prefer you don't disturb their nest holes too much. Apart from birds, there are a few vertebrates on the site. The common lizard, grass snake sand adders have been seen, but only rarely. (If you do see a snake, be very pleased. Do please let me know, do not under any circumstances try to hurt them: they are scarce and protected). Foxes and roe deer are often seen, but badgers seem never to come on site, disliking heavy clay). Small mammals - rodents and shrews - are under-recorded though doubtless present. One final group of mammals deserves mention: there is a small summer colony of pipistrelle bats roosting in the entrance tunnel, and at dusk in June-July they are easily seen hunting in the dusk by the tunnel. I am happy to bring along a bat detector if anyone wants to hear them calling. The reserve changes character hugely between summer and winter. All summer the site is dry, the only permanent water being the southern boundary ditch. However from roughly October to April water wells up out of the ground from many small springs, the pond fills up, and wellingtons are utterly vital footware! The exact path by which the water wells up is unclear to me, but seems to correspond to stony (hence permeable) layers in the otherwise utterly impermeable clay. I remain amazed at how much water flows into the site given the apparently small catchment area available and would be interested to hear from anyone who knows about the hydrology of these strata. The best time to appreciate this effect is after a few days of hard frost, when pillows of ice, metres wide, can be seen projecting several cm above the ground in a few places, pushed up by the pressure of water welling up from underneath. I have set up a web site about the reserve at http://www.chezshaw.demon.co.uk/claypit/index.htm and can be contacted at p.shaw@roehampton.ac.uk. Currently my mobile is 07985 431703, but inevitably this will change: the current contact number will always be posted on the interpretation board by the site entrance. Peter Shaw January 2009.