There are three related types of Neolithic earthwork that are all sometimes loosely called henges. The essential characteristic of all three is that they feature a ring-shaped bank and ditch, with the ditch inside the bank. Because the internal ditches would have served defensive purposes poorly, henges are not considered to have been defensive constructions. The three henge types are as follows, with the figure in brackets being the approximate diameter of the central flat area:Henge (> 20 m). The word henge refers to a particular type of earthwork of the Neolithic period, typically consisting of a roughly circular or oval-shaped bank with an internal ditch surrounding a central flat area of more than 20 m (66 ft) in diameter. There is typically little if any evidence of occupation in a henge, although they may contain ritual structures such as stone circles, timber circles and coves. Henge monument is sometimes used as a synonym for henge. Henges sometimes, but by no means always, featured stone or timber circles, and circle henge is sometimes used to describe these structures. The three largest stone circles in Britain are each within a henge. Examples of henges without significant internal monuments are the three henges of Thornborough Henges. Although having given its name to the word henge, Stonehenge is atypical in that the ditch is outside the main earthwork bank. Hengiform monument (5 – 20 m). Like an ordinary henge, except the central flat area is between 5 and 20 m (16–66 ft) in diameter, they comprise a modest earthwork with a fairly wide outer bank. The terms Mini henge or Dorchester henge are sometimes used as synonyms for hengiform monument. An example is the Neolithic site at Wormy Hillock Henge. Henge enclosure (> 300 m). A Neolithic ring earthwork with the ditch inside the bank, with the central flat area having abundant evidence of occupation and usually being more than 300 m (980 ft) in diameter. Some true henges are as large as this, but lack evidence of domestic occupation. Super henge is sometimes used as a synonym for a henge enclosure. However, sometimes Super henge is used to indicate size alone rather than use, e.g. "Marden henge ... is the least understood of the four British 'superhenges' ".
