DENE-HOLES, the name given to certain caves or excava tions in England, popularly but incorrectly attributed to the Danes. The word however is probably derived from the Anglo Saxon den, a hole or valley. There are many underground excava tions in the chalk districts of the south of England, but true dene holes are found chiefly in those parts of Kent and Essex along the lower banks of the Thames.
The general outline is invariably the same. The entrance is a vertical shaft, some 3ft. in diameter, falling sometimes to a depth of 6oft. The depth is regulated by the depth of the chalk from the surface, but although chalk could have been obtained close at hand within a few feet, or even inches, from the surface, a depth of from 45 to 8oft., or more, is a characteristic feature. The shaft, when the chalk is reached, widens out into a domed chamber with a roof of chalk some 3ft. thick. The walls frequently contract somewhat as they approach the floor. As a rule there is only one chamber, from 16 to 18f t. in height, beneath each shaft. From this excessive height it has been inferred that the caves were not pri marily intended for habitations or even hiding-places. In some cases the chamber is extended, the roof being supported by pillars of chalk left standing. In a rare specimen of a twin-chamber dis covered at Gravesend, the one entrance served for both caves, although a separate aperture connected them on the floor level. Where galleries are found connecting the chambers, forming a bewildering labyrinth, they are usually the work of a people of a much later period than that of the chambers.
Isolated specimens have been discovered in various parts of Kent, Essex, Hants and Berks, but the most important groups are at Grays Thurrock, in the districts of Woolwich, Abbey Wood and Bexley and Gravesend. Some of the Chislehurst caves may have been begun as dene-holes, but if so, they have been so enlarged and altered that their original character has been obliterated.
The tool work on the roof or ceiling is generally rougher than that on the walls, where an upright position could be maintained. Casts taken of some of the pick-holes near the roof show that, in all probability, they were made by bone or horn picks. And numerous bone picks have been discovered in Essex and Kent. These pick-holes have assisted in fixing the date of their formation to pre-Roman times. Very few relics of archaeological value have been discovered in any of the known dene-holes, to assist in fixing the date or determining their uses. Pliny mentions pits sunk to a depth of a hundred feet, "where they branched out like the veins of mines." This has been used in support of the explanation that dene-holes were wells sunk for the extraction of chalk. Chretien de Troyes has a passage on underground caves in Britain which may refer to dene-holes, and tradition of the i4th century treated the dene-holes of Grays as the fabled gold mines of Cunobeline (or Cymbeline) of the 1st century. Vortigern's caves at Margate are possibly dene-holes adapted by later peoples to other purposes; and excellent examples of various pick-holes may be seen on differ ent parts of the walls. Local tradition associates these caves with smugglers; and since illicit trade was common both on the coast and in the Thames up to Barking Creek, the theory is tenable.
There are three purposes for which dene-holes may originally have been excavated; (a) as hiding places or dwellings, (b) as draw-wells for the extraction of chalk for agricultural uses, and (c) as store-houses for grain. It is unlikely that they were used as habitations, although they may have been used occasionally as hid ing-places. Against the theory that they were primarily designed for the extraction of chalk, it may be urged that chalk could have been obtained on the surface close by, and that known examples of chalk draw-wells do not descend to so great a depth. The dis covery of a shallow dene-hole, about i4ft. below the surface, at Stone, negatives this theory still further. The view that these pre historic excavations were designed as silos is usually accepted as the most probable. Silos, or underground storehouses, are well known in the south of Europe and Morocco. It is supposed that the grain was stored in the ear and carefully protected from damp by straw. A curious smoothness of the roof of one of the chambers of the Gravesend twin-chamber dene-hole supports this theory. The theory that the excavations were made in order to get flints for implements is quite impossible, as a careful examination of a few examples will show.
See F. C. J. Spurrell, "Deneholes and Artificial Caves," in the Archaeological Journal (1882) ; T. V. Holmes, "Deneholes" (1883) and many other references in the Essex Naturalist; Archaeologia Cantiana (vol. xviii., 1896) ; F. W. Reader, "Deneholes" in Old Essex, ed. A. C. Kelway (1908) ; W. Johnston, Folk Memory (1908) with bibliography.