Prehistoric platform cairn, settlement and field system at Pernagie, St Martin's


Heritage Category: Scheduled Monument

List Entry Number: 1018110

Date first listed: 24-Jul-1998


Ordnance survey map of Prehistoric platform cairn, settlement and field system at Pernagie, St Martin'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. Martin's

National Grid Reference: SV 91920 16808


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. Platform cairns are funerary monuments of Early Bronze Age date (c.2000-1600 BC). They were constructed as low flat-topped mounds of stone rubble, up to 40m in external diameter though usually considerably smaller, covering single or multiple burials. Some examples have other features, including peripheral banks and internal mounds constructed on the platform. A kerb of slabs or edge-set stones sometimes bounds the edge of the platform, and a peripheral bank or mound if present. Platform cairns can occur as isolated monuments, in small groups or in cairn cemeteries. In cemeteries they are normally found alongside cairns of other types. Platform cairns form a significant proportion of the 387 surviving cairns on the Isles of Scilly; this is unusual in comparison with the mainland. All surviving examples on the Isles of Scilly are considered worthy of protection.

The platform cairn and house platform settlement at Pernagie survive well; the settlement site has not been excavated and despite remains from much later structures causing some modification to the cairn's upper surface, the disturbance is limited and evidence still survives for the cairn's underlying funerary structure. This cairn and settlement are an unusual survival within low-lying areas enclosed during the post-medieval period and consequently they are of considerable value for our understanding of prehistoric land use at these levels, complementing the evidence from the more extensive survivals on higher land as on the neighbouring Top Rock Hill.


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


The monument includes a prehistoric platform cairn and nearby settlement and field system on a small knoll at the south of Pernagie, a low coastal strip on the north west coast of St Martin's in the Isles of Scilly. The prehistoric features occur within the area of a largely dismantled post-medieval field system, with remains of a small building built onto the cairn. The scheduling also includes an area of prehistoric field system to the west of the cairn. The cairn is visible on the summit of the knoll as a roughly circular mound 13m in diameter, rising 1.5m high from the knoll's steep northern slope but only 0.3m from the crest of the knoll on the south to a flattened upper platform approximately 5m in diameter. In the ESE of the upper surface is a small bedrock outcrop, 0.7m high, and along the southern edges of the platform a curving line of spaced small bedrock outcrops project from the turf to give the effect of a spaced kerb, supplemented on the south east by an artificially edge-set slab. The centre and eastern half of the mound's upper surface contain the lower course and adjacent tumble of slab-built walling deriving from a small early post-medieval building founded upon remains of the cairn's funerary structure. The building's remains include, east of centre on the cairn, a north-south wall of four edge-set slabs, to 1.2m long and 1m high, ending on the south at a corner with another edge-set slab extending west. Within the wall's corner is a fallen slab but embedded in the turf beyond it, the upper edges of a line of further buried slabs extend north for 2.75m, parallel with, and 1.5m west of, the exposed north-south wall. The rectangular arrangement across the cairn's centre formed by the exposed walling and the buried line of slabs closely resembles in size and position the box-like funerary structures called cists known from several other prehistoric cairns on Scilly. Along the east of the building's exposed wall is a hollow 1.3m wide and 0.7m deep, fringed on the east side by tumbled wall slabs; the hollow is constricted at the south by the small bedrock outcrop, from which a ridge of exposed rubble runs west to the building's wall corner. Beyond the building, the north east periphery of the cairn's mound is over-ridden by the corner of a post-medieval field wall which extends to the north and ENE. The prehistoric settlement site is situated on the lower south eastern slope of the knoll, from about 15m south east of the platform cairn. It is visible as a close grouping of at least two house platforms, each visible with an ovoid interior approximately 7m long by 5m wide, levelled into the lower slope to give a steep backscarp generally 1.5m high and bearing traces of a rubble revetment facing. Opposite the backscarp, the forward edge of their interiors are defined by a rubble wall up to 1.5m wide and 0.5m high from the platform interior but dropping 1.5m externally. The prehistoric cairn and settlement, and the post-medieval building, occur within a post-medieval field system depicted on 19th and early 20th century Ordnance Survey maps but extensively dismantled and robbed of its wall stone since then. In addition to its upstanding walling on the north east periphery of the cairn as noted above, and further such walling on the eastern slope of the knoll, surviving traces of an earlier, prehistoric, field system include slight turf-covered banks extending 10m west from the cairn's southern edge and along the upper southern slope of the knoll to meet another slightly angled bank crossing the low ridge west of the knoll, heading north over its northern half and south west over its southern half. A further low bank extends 15m west along the ridge's spine from the angle in the bank across the ridge; near its western end it incorporates a cluster of natural outcrops, beyond which it turns SSW towards the headland's southern coast. Beyond this scheduling, a cairn cemetery associated with prehistoric field systems and settlement sites extend across Top Rock Hill and its flanks, the neighbouring upland area to the east on St Martin's.

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: 15518

Legacy System: RSM


Books and journals
Ashbee, P, Ancient Scilly, (1974)
Russell, V, Isles of Scilly Survey, (1980)
Russell, V, Isles of Scilly Survey, (1980)
Thorpe, C/CAU, AM 107 for Scilly SMR entry PRN 7187, (1988)
Thorpe, C/CAU, AM 107 for Scilly SMR entry PRN 7187, (1988)
Title: 1:2500 Ordnance Survey Map; Cornwall sheet LXXXII: 11 Source Date: 1889 Author: Publisher: Surveyor: Both 1889 and 1908 editions
Title: 1:2500 Ordnance Survey Map; Cornwall sheet LXXXII: 11 Source Date: 1889 Author: Publisher: Surveyor: Both 1889 and 1908 editions
Title: 1:2500 Ordnance Survey Map; Cornwall sheet LXXXII: 15 Source Date: 1889 Author: Publisher: Surveyor: Both 1889 and 1908 editions
Title: 1:2500 Ordnance Survey Map; SV 9116 Source Date: 1980 Author: Publisher: Surveyor:

End of official listing