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Underground Kent : Dene Holes, Chalk Wells and other Works. The post-AGM lecture this year was given by Rod LeGear of the Kent Underground Research Group. The large audience of members and visitors who gathered in Greenstreet Methodist Church Hall on 27th October, enjoyed Rod’s wide-ranging talk. Not only did he cover perforations in the chalk, but also various tunnels and galleries in ragstone and greensand beds. Several myths were dispelled: the galleries that radiated from the bottom of dene hole shafts were the result of excavation of chalk to be used to ‘sweeten’ the often acid clay soils surfacing the fields above. Tales of tunnels connecting the vicarages to the churches, allowing smugglers, or Royalists, to escape pursuers, were largely the stuff of legend. Theories about Stone Age miners digging for flints with deer-antler picks also lacked substance. Even the Druidic mystique of the Shell Grotto (visited on a members’ trip earlier in the year) was dismissed: a dene hole converted to an 18th century ‘folly’ was Rod’s conclusion. No: most dene holes and the larger, cylindrical, ‘chalkwells’, were the result of excavation for agricultural purposes (‘marling’) from the 17th to the 20th century. Engineering aspects were touched on. Roof-falls could be avoided in chalk by excavating galleries with a tall ‘gothic arch’ shape. Timber props were not used. Curiously, creating these great vaulted ceilings relied on miners cutting from the ceiling downwards on a chalk platform that lowered as the mining progressed. This left a shelf that has from time to time led people believe they might have been sacrificial platforms. Nothing of the kind! It was also quite feasible to mine into the soft Kentish beds of sand. But care had to be taken in all cases not to be too greedy. Cutting away at supporting columns, just because it was convenient, could result in disaster! Several ‘human’ stories were covered, for instance the sudden difficulty of residents of a housing estate to obtain subsidence insurance when it was revealed that a myriad of chalk galleries intertwined below; the refusal of the MoD to allow Rod’s group to survey Dover cliff caves, once top secret military installations, ‘because there were no caves’; the use of the massive caverns at Chislehurst as wartime air-raid shelters, and the several instances of people vanishing down poorly plugged shafts. Plugs were often no more than earth piled on a tree trunks and shrubs braced across the hole before piling earth on top - over the years, these temporary structures rot, rain falls to make the plugs heavier and losen .... and finally the hole opens up dramatically and unpredictably! The lecture ended with a barrage of questions and wartime experiences. It had been a most enjoyable and informative evening. Bob Baxter. |