49 Cornish Archaeology 59, 2020, 49–75 Investigations at Trethevy Quoit 2019: the anatomy of a Cornish portal dolmen ANDY M JONES with a contribution from ANNA LAWSON-JONES Trethevy Quoit is one of the best-preserved Early Neolithic portal dolmens both in Cornwall and in the British Isles. In 2019 Cornwall Archaeological Unit, in partnership with Cornwall Heritage Trust and Cornwall Archaeological Society, undertook two geophysical surveys, followed by test pitting. Test pits excavated near to the quoit revealed a platform measuring approximately 10m by 25m constructed of quarried and deliberately fragmented pieces of metamicrogabbro stone (an intrusive igneous rock), which had been brought to the site from a local source. Study of the granite slabs of the quoit itself suggests that they were all from the same outcrop, a good candidate being the Caradon Hill area, approximately 1.5 km away. The site is discussed in the context of Cornish chambered tombs, portal dolmens more widely, and the significance of the use of different materials. The results from the project were significant as they have revealed that Trethevy Quoit was a designed monument comprised of selected stones from a specific source, set upon a platform of quarried green-coloured stones. As such, it would have stood out as a visually striking monument in the landscape, which in the Early Neolithic would have been almost entirely devoid of built structures. In July 2019, archaeological investigations at Trethevy Quoit, St Cleer (Fig 1), were undertaken over a five-day period by Cornwall Archaeological Unit in partnership with Cornwall Heritage Trust and Cornwall Archaeological Society. The project was grant funded by Historic England, Cornwall Heritage Trust and Cornwall Archaeological Society. Trethevy Quoit was designated a scheduled monument in 1923 (National Heritage List for England 1017579) and in 1931 was gifted to the state; more recently it has been in the care of Cornwall Heritage Trust (CHT), on behalf of English Heritage. However, protection was limited to the visible monument and a 2m buffer zone around it. In 2017 CHT, supported by a grant from Historic England, took the opportunity to purchase the 1.25 ha field in which the monument stands, to safeguard its setting. The overall aim of the project described here was to obtain additional information on the extent and form of the monument, as well as evidence for activities in the area around it, which would help with future interpretation and management of the quoit and its setting. The first core objective was to undertake a geophysical survey of the entire field in advance of the excavation, in order to better understand the archaeological potential in the field as a whole, as well as features associated with the quoit.