Archaeological excavations on a large mound in South Walls (Orkney, Scotland) suggest that it does not contain a broch. Instead, it appears to be a Neolithic chambered cairn.
     A two-week excavation of Outer Green Hill recently drew to a close. Excavation supervisor was Dan Lee, from the Orkney Research Centre of Archaeology (ORCA). He explained: "Outer Green Hill was interesting as it did not display the geophysical responses typical of a broch - large outer ditches, associated settlement and circular internal walls. The geophysics results suggested a squared internal structure, perhaps more indicative of a Neolithic tomb, a period only represented by the Dwarfie Stane in North Hoy, or a Norse stronghold, as the area is mentioned in the sagas."
     The aim of the dig was to characterize and date the site. "A trench excavated from the top of the mound, down the southern side, revealed two internal corbelled wall faces, just over one metre apart, that appear to form an internal passage orientated east to west," said Dan. "It appears to form the central passage of a Neolithic chambered tomb. Corbelled internal walls, where the walls gradually taper inwards, towards the roof, are more typical of Maeshowe-type tombs. Waterworn beach slabs have also been used in the internal wall faces, in the same way as at the Quoyness chambered tomb in Sanday. The loose upper backfill of the passage contained several pieces of pottery dating to the Neolithic, although this awaits specialist conformation." Other finds included animal bone and a quartz scraper, found in the topsoil.
     The structure of the external mound, to the south, consists of a solid wall-like core, with an external revetment wall that slopes inwards, and which survives to over one metre in height. Dan said: "It is possible that the passage represents an internal feature of the outer wall of a broch, rather than the central passage of a Neolithic tomb, however the pottery and character of the masonry point to a Neolithic date."

Source: Orkneyjar (9 July 2008)