The monument consists of a large area of stony moorland, scattered with worked outcrops and debris associated with prehistoric stone implement manufacture, within which are located a lintelled gallery and a chambered burial cairn.
In the 1940s a lintelled gallery was recorded at HU 32669007. This has been constructed by roofing over a gully created by the removal of an outcrop of the distinctive local felsite rock to manufacture stone implements. Subsequent examination of the area has revealed a large number of working areas, liberally scattered with flakes and broken implement rough-outs. The working areas take the form of sub- circular platforms built largely out of flaking debris, and often lie in slightly sheltered locations. Implements seem to have been taken to a rough stage only on the site, prior to being removed elsewhere
for polishing. The final products were typical Neolithic polished axes and also a number of flat knives, of a type unique to Shetland. The foundations of a chambered cairn, consisting only of the kerbstones of a passage and chamber, lie within the working area, at HU32899003.
The area to be scheduled is irregular, bounded on the N by the S shore of Mill Loch and the stream which feeds it from the W, on the W by the small valley of Inni Scord, on the S by a line drawn from the NE corner of Inniscord Lochs to the N corner of Mousa Water and on the E by a line from the same N corner of Mousa Water to the shore of Mill Loch. This area, which includes the gallery, chambered cairn and
a large number of working areas, is marked in red on the accompanying map.