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The Deneholes of Hangman’s Wood

A description of a little-known type of underground feature written by Derek Sanderson and Roger Wing.

The Deneholes are phenomena which may be of interest to cavers - particularly as some of them can still be explored.  Indeed, some members may be familiar with them whilst others may merely have read about them.  They are found in a number of counties in the South East of England and also in parts of France, and one of the main concentrations is in Essex, occurring in the comparatively small area known as Hangman's Wood, Greys.  There is a soft spot in the hearts of the authors for the Deneholes, as they represent an early landmark in their caving careers.

DESCRIPTION. Basically, all Deneholes consist of a single shaft dropping vertically from the surface through the thin topsoil of the region and the underlying Thanet Sand, and terminating in a chamber in the chalk beneath, which may be at a depth of up to eighty feet.  These shafts vary in diameter, but are usually between ten and twelve feet wide and are reminiscent of a well shaft.  The chambers at the bottom vary in shape from simple bell like chambers to more complex chamber patterns.  The Deneholes found at Crayford, Kent are of the simple bell-like variety, whilst those at Stankey are more irregular.  The most common form of chamber is the 'double trefoil' shape as is found at Hangman's Wood.  Originally, there were many shafts at Greys, but now there are only two shafts open (70' ladder required for each).  Below is a network of chambers interconnected by short rabbit-hole-like crawls.  All is dry and mostly horizontal.

AGE.  To establish their age is by no means easy, but one may hazard a guess from various pieces of evidence.  In 1884 and 1887, the Deneholes complex of Greys was fully investigated on behalf of the Essex Field Club by two of its members - T.V. Holmes and W. Cole.  An extensive report was published in which they discussed some of their findings. They found, for instance, pieces of Niedermendig lava which was quarried in the Eifel district of Germany and not imported into this country until the arrival of the Romans.  This, in itself, is of dubious value, though it may add weight to other evidence.

The most useful evidence concerning age comes from the bones found in the deposits that have inevitably settled at the bottom of the shafts.  These include remains of sheep; badger; ox; dog; horse and man.  What is significant is the total absence of red deer and wolf, which were apparently common in the time of the Normans.

One may suggest, then, that the Deneholes were dug soon after the arrival of the Normans, and this seems to be the conclusion arrived at by Baker when he wrote, '…the assumption that they existed in Saxon times will hold no more water than a chalk Denehole would.' (Caving, p102).  They do, however, predate the trees which grow around them.

REASON FOR EXISTENCE. This leads to the engaging problem of why they are there, and several theories have been put forward over the years.

  1. The shafts are, in fact, natural.  This is a recent theory.  What has been supposed is that a cavity has been formed in the chalk bed by percolating water in a similar manner to that which occurs in Limestone.  This cavity is formed close to the top of the chalk layer.  The theory goes that eventually the roof of the cavity meets the underside of the layer of Thanet sand above, and this drains through like an egg-timer to leave a cylindrical shaft dropping into a semi-filled chamber in the chalk beneath.

    No matter how feasible this theory may seem, it cannot hope to explain the ‘double trefoil’ shape of the chambers.  Add to this the problem of balancing the infill with the volume of the shaft, and the theory loses credibility - regardless of whether such a formation process is at all feasible.
  2. An equally implausible view is that they were gold mines.  1705, a Dr. Pert wrote a Natural History of Oxfordshire, in passing, he referred to the Deneholes as 'the gold mine of Cunobeline in Essex.'
  3. That they were flint mines.  There are several points against this view.  Firstly, a band of flint can be seen in both the open shafts of Hangman's Wood, but this flint has not been touched.  Secondly, there are no signs of debris either inside or outside the Deneholes, and this would be the first time a flint mine had been cleared up.
  4. That they were Roman burial chambers.  Some burial urns were found by a Mr. Neeson, but not in the Deneholes of Hangman's Wood, and both the dating and design of the chambers run against this view.
  5. That they were cave dwellings.  Clearly, this is wrong.  Cave dwellings are invariably littered with the remains left by the inhabitants.  No such remains have been found in Hangman's Wood.
  6. That they were places of refuge.  According to Baker, this theory seems to have gained weight from the fact that locally, the word 'Denehole' is pronounced 'Danehole' implying a hiding place from the Danes.  However, several commentators, including Baker, have observed that the word is derived from the Anglo-Saxon word 'Denn' which simply means 'Cave' or 'den'.  Also, the nature of the Deneholes themselves suggests that they are the last place that one would wish to use as a refuge.  Once in, it would be an easy matter to become trapped.
  7. That they are pitfalls, or some form of animal trap.  Clearly, this is not a feasible theory, as the Deneholes are too elaborate in construction.
  8. That they were granaries.  This theory was much favour by Holmes and Cole, and they arrived at this conclusion by drawing an analogy between the Deneholes and other under ground constructions which are definitely silos.  However, where these silos are concerned, there has always been an abundance of evidence as to their use - evidence which the Deneholes have not displayed.
  9. That they were chalk mines, either for local marling or for commercial uses.  This theory seems to be the most likely, and was accepted by Baker, though a few questions may still spring to mind.  Firstly, why mine chalk at Hangman's Wood when there is a large outcrop of the rock barely two miles away?  There may be several possible answers to this, such as the cost or inconvenience of transport, or different ownership of the land where the outcrop occurs.  Secondly, why are the chambers shaped the way they are?  Baker attempts to explain the trefoil shape in terms of how far a bucket on the end of a rope will swing from the main shaft, but this is not completely satisfactory.  Rather they are shaped in this way for purposes of structure.  Some of the walls between chambers of one shaft and another are only a matter of feet thick, so they have been dug with a sense of precision.  There is very little evidence of collapse which implies that the diggers knew when to stop digging 'one chamber and start another.  The trefoil shape may be the natural outcome of the maximum removal of chalk with the minimum of risk.

SIGNIFICANCE OF AGE. It may have been noted that the Deneholes at Greys were tentatively dated as post-Norman, while elsewhere Mr. Meeson found some Roman urns suggesting a pre-Norman date.  The conclusion to be drawn from this is that not all Deneholes were dug in the same period and that they were dug when and where necessary.  This would imply that, whatever their purpose was, it was an agricultural or industrial one rather than being the result of an invasion or some other occurrence which can be accurately dated.

ACCESS.  Access is controlled by Thurrock U.D.C. who issues a descent licence for those who are prepared to abide by a number of simple rules and fill in an insurance slip.  Address to write to is: Recreation Manager, Recreation Department, Blackshots Lane, Grays, Essex, RM13 2JU.  There is a lot of serious research still to be done in connection with Deneholes.

References

Caving (E.A. Baker)
Forgotten Thameside (Glyn H. Morgam) 1951.
Deneholes and other Chalk Excavations (Rev. J.W. Haynes)
Journal of Royal Anthropological Institute.39,1909.
Victoria County History of Essex. (G. Gould.)
Essex Field Club Report. (T.V. Holmes & W. Cole) Essex
Naturalist. Vol 1,1887.