Dene Holes
Dene Holes
Many deep narrow shafts dug in the chalk soil have been found over much of the South East of England, including that land inhabited by the Cassii. These are commonly known as 'Dene Holes'. This name is believed to have come from the Saxon 'Deon Tigh' - Harvest Home. As the name suggests, and for many years, it was believed that these holes were dug for the purpose of storing gathered grain crops. Legend carried a suggestion that the Dene Holes would have been filled with the supervision of Druids and, according to their way, possibly at night time and with 'much ritual'. It can be understood why this romantic legend was perpetuated !
A publication written by R. F. Le GEAR dated 1992 establishes the real reason for these holes. The purpose was for extracting the chalk that lay beneath and under the Thames Sand. The holes date from before Roman times and were mined right up until the turn of the 20th century. The earth under the fields was known to be acidic. Since before Roman times it has been known that chalk is alkaline. The spreading of the chalk on to fields - known as 'chalking' or 'marling' - replacing the calcium lost through rainfall - fertilised and made the earth 'sweeter'. The holes were dug beside fields where the chalk could be easiest used. That is why there are collective groups of them.
Chalk also had other uses viz.; building purposes ( footings ), burning to form lime for lime mortar and repairing roads. R. F. LeGEAR describes that the Dene hole method of obtaining chalk had much to recommend it. A small shaft at the edge of a field would not require the removal of a large area of overburden as in open cast mining, and the shaft would not interfere with farming operations and could easily be blocked off when mining ceased. He goes on to say that a question that the reader could ask is .... " why dig a shaft say 50ft deep when the chalk occurs near the surface a few hundred yards away ?..." The answer is that the chalk was probably on someone else's land. Also the farmers preferred chalk from a depth claiming it was 'fatter'. This has some truth as chalk near the surface has certain associated elements leached out. The most common way of sealing an exhausted Dene hole was to throw a bush or tree stump down the neck of the hole and then fill with earth etc.
As years have gone by the wood has rotted and the fill material has fallen to the chambers below leaving a dangerous gaping hole. These chasms still appear from time to time and make the local news. Gravel and sand lie under Dartford Heath therefore, apart from a couple of them found near Crayford, no Dene Holes exist there.
