The Hambledon Hill Early Neolithic causewayed enclosure lies in north-east Dorset. The main enclosure is divided from the radiating spurs by pairs of cross dykes. This was originally thought to be the site of a Neolithic cross dyke. During his 1974-86 campaign of excavations on Hambledon Hill, Roger Mercer speculated that there may have been a similar cross dyke running across the narrow neck of land connecting the central summit to the northern, hillfort spur. Any such cross dyke would be expected to have been destroyed by the construction of the gateway annexe to the Iron Age hillfort.
The earthworks on Hambledon Hill were surveyed by RCHME in 1996. The survey identified a trace of bank 0.2 metres high, which could have been the remnant of the innermost element of such a cross dyke. Located at the southwest corner of the gateway annexe, it extends for only 15 metres east-west, on a slightly different alignment from the Iron Age counterscarp bank which seems to overlie it. If the earthwork were similar in form to the other cross dykes, it would have been all but destroyed by the construction of the outer ditch of the gateway annex, as suggested by Mercer.
A reassessment of the aerial photographs has indicated that the earthworks are not of Neolithic date. A series of shallow scoops in the upper edge of the southernmost Iron Age ditch are possibly from the incorporation of an earlier Iron Age segmented ditch; a low scarp from the north end of the Iron Age gateway annexe could possibly be part of a cross dyke, although its alignment would make this unlikely.