Prehistoric house platform and boundary north east of Carn Leh, St Mary's


Heritage Category: Scheduled Monument

List Entry Number: 1015670

Date first listed: 21-Jan-1999


Ordnance survey map of Prehistoric house platform and boundary north east of Carn Leh, St Mary's
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The building or site itself may lie within the boundary of more than one authority.

District: Isles of Scilly (Unitary Authority)

Parish: St. Mary's

National Grid Reference: SV 91306 09897


Legacy Record - This information may be included in the List Entry Details.

Reasons for Designation

The Isles of Scilly, the westernmost of the granite masses of south west England, contain a remarkable abundance and variety of archaeological remains from over 4000 years of human activity. The remote physical setting of the islands, over 40km beyond the mainland in the approaches to the English Channel, has lent a distinctive character to those remains, producing many unusual features important for our broader understanding of the social development of early communities. Throughout the human occupation there has been a gradual submergence of the islands' land area, providing a stimulus to change in the environment and its exploitation. This process has produced evidence for responses to such change against an independent time-scale, promoting integrated studies of archaeological, environmental and linguistic aspects of the islands' settlement. The islands' archaeological remains demonstrate clearly the gradually expanding size and range of contacts of their communities. By the post- medieval period (from AD 1540), the islands occupied a nationally strategic location, resulting in an important concentration of defensive works reflecting the development of fortification methods and technology from the mid 16th to the 20th centuries. An important and unusual range of post- medieval monuments also reflects the islands' position as a formidable hazard for the nation's shipping in the western approaches. The exceptional preservation of the archaeological remains on the islands has long been recognised, producing an unusually full and detailed body of documentation, including several recent surveys.

The early linear boundaries of the Isles of Scilly were constructed from the Bronze Age to the early medieval period (c.2000 BC to AD 1066): closer dating within that period may be provided by their visible relationships to other classes of monument or by their relationship to an earlier recorded sea level. They consist of stone walls, up to 3m wide and 1.1m high but usually much slighter and sometimes covered by later deposits. They served a variety of functions including: separating land regularly cultivated from that less intensively used; separating land held by different social groups, or delineating areas set aside for ceremonial or religious activity. Linear boundaries on the coastal margin of the islands are often indistinguishable from truncated upper walls of early field systems, the rest of whose extent has been destroyed by the rising sea level. As one element within wider systems of landscape subdivision, linear boundaries may have a close physical relationship to contemporary settlement sites including house platforms: rounded or polygonal areas levelled into a slope and with interiors defined by the levelling backscarp, sometimes faced with stone, and often with a bank along the perimeter of the forward edge. Excavations have shown that some house platforms supported timber and stone built houses whose post holes, lower courses and occupation surfaces are masked beneath later deposits. Their relationships with datable field systems and finds from excavations indicate that house platforms were constructed over a similar period to linear boundaries. Both linear boundaries and house platforms provide significant insights into the physical and social organisation of past landscapes. This house platform beside Carn Leh survives well. Despite truncation of the adjacent boundary by coastal encroachment, both the house platform and boundary provide evidence for the presence and nature of early land use in an area now largely submerged by rising sea levels. Their survival at such a low level complements the patterns of broadly contemporary field system and cairn cemetery survivals on the higher land of Peninnis Head and thereby contributes to our wider view of land use and settlement organisation among prehistoric communities in the pre-submergence landscape of Scilly.


Legacy Record - This information may be included in the List Entry Details.


The monument includes a prehistoric house platform and adjacent linear boundary on the north eastern coastal margin of Carn Leh, a prominent natural outcrop at the south west of the entrance to Old Town Bay on the south coast of St Mary's in the Isles of Scilly. The house platform is visible as a sub-circular hollow with a 4.2m diameter flattened base sloping slightly to the north east and levelled into the steeper north eastern slope close to the base of the Carn Leh outcrop. The levelling produces a steep backscarp, to 0.5m high, along the south west of the platform; rubble facing is detectable through the turf covering the backscarp, changing to a wall of at least five slabs in line, extending 2.8m along the north west of the platform and ending on the north at a large boulder, 1m long and 0.7m high. On the north east, the interior is defined by a very slight raised bank, 0.3m wide and 0.2m high, behind the present coastal edge. From the platform's north western walling, the adjacent linear boundary extends north west then curves to the north before being truncated by this present coastal cliff to give a surviving length of 9m. The boundary is visible as a turf-covered bank generally 1.5m wide and 0.4m high, with its rubble fabric exposed where it runs into the cliff edge. Beyond this scheduling the walls and banks of a prehistoric field system extend along the eastern flank of Peninnis Head from 230m to the south west, with a prehistoric cairn cemetery on the higher land of that promontory. Beyond the south of this scheduling is the much later embanked defended area of a Civil War gun battery on the south eastern coastal margin of Carn Leh.

MAP EXTRACT The site of the monument is shown on the attached map extract. It includes a 2 metre boundary around the archaeological features, considered to be essential for the monument's support and preservation.


The contents of this record have been generated from a legacy data system.

Legacy System number: 15485

Legacy System: RSM


Parkes, C & Herring, P, Scilly SMR entry PRN 7709, (1990)
Parkes, C & Herring, P/CAU, Scilly SMR entry PRN 7709, (1990)
Title: 1:2500 Ordnance Survey Map; SV 9109 Source Date: 1980 Author: Publisher: Surveyor:

End of official listing