Kerbed platform cairn and prehistoric field system north west of Porth Morran, White Island


Heritage Category: Scheduled Monument

List Entry Number: 1010161

Date first listed: 07-Oct-1976

Date of most recent amendment: 20-Feb-1995


Ordnance survey map of Kerbed platform cairn and prehistoric field system north west of Porth Morran, White Island
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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 92229 17498


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 built 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 where they represent a far smaller proportion of the known total. All surviving examples on the Isles of Scilly are considered worthy of protection. Irregular field systems are one of several methods of field layout known to have been employed in the Isles of Scilly from the Bronze Age to the Roman period (c.2000 BC - AD 400); closer dating within that period may be provided by the visible relationships of the field boundaries to other classes of monument with a shorter known time-span of use, or by their relationship with an earlier recorded sea level. They comprise a collection of field plots, generally lacking in conformity of orientation and arrangement, containing fields of varying shapes and sizes, bounded by rubble walls or banks, often incorporating edge-or end-set slabs called orthostats. Some irregular field systems on the Isles of Scilly contain a distinctive association, rarely encountered elsewhere, whereby certain of their field boundaries directly incorporate or link cairns, entrance graves and cists in some groups of prehistoric funerary monuments. Although no precise figure is available, irregular field systems form one of the three principal forms of prehistoric field system, along with regular field systems and some groups of prehistoric linear boundaries, which survive in 71 areas of the Isles of Scilly. The disposition of both platform cairns and irregular field systems provide significant insights into the physical and social organisation of past landscapes and the relationships between settlement and funerary activities.

The kerbed platform cairn in this monument has survived well and has not been excavated. The field system, although surviving as a truncated portion of its former whole, provides a major part of the surviving evidence for the extent and nature of prehistoric settlement activity in the vicinity of the cairn group. The relationship between the cairn group and the field system illustrates the organisation of land use among prehistoric communities. The wider relationships between this monument, the other varied types of funerary cairn and prehistoric field system on White Island, and the evidence for the submergence of settlement areas since they were built, demonstrate in a dramatic way the major environmental changes that have affected the setting of some surviving prehistoric monuments since their construction.


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


The monument includes a prehistoric kerbed platform cairn situated beyond the eastern side of an elongated truncated portion of broadly contemporary field system extending up the SSW shoulder of the northern hill of White Island, off St Martin's in the Isles of Scilly. The cairn is located at the western end of a group containing at least nine prehistoric cairns of various types dispersed over the northern half of White Island. The platform cairn survives with a circular mound of heaped rubble, 5.5m in diameter, rising 0.4m high to a flattened upper platform. A row of edge- and end-set slabs forms a kerb around the perimeter of the mound. The cairn is situated 20m beyond the eastern side of the surviving part of a prehistoric irregular field system. The field system survives with two adjoining fields contained within an elongated tapering strip of land of 0.06ha defined by an outer wall of edge-set slabs, up to 0.7m high and 1m wide, though generally 0.4m high. This strip is a maximum 18m wide where truncated by the present coastal edge at its SSW end. From there, it extends for 45m to the NNE, directly upslope, with straight converging sides, to measure 8m wide at its blunt rounded NNE end. The area within the field system's outer wall is noticeably free of most of the surface stone that forms a scatter across the surrounding ground and reflects deliberate clearance during the field system's use. The overall strip enclosed by the wall is divided into the two surviving fields of this field system by a transverse bank, running WNW-ESE across the strip 5m before the coastal truncation of its SSW end. The bank is 0.25m high, largely turf-covered but with one edge-set slab and a little rubble visible; however the uphill side of the bank is masked by a build-up of deposits, called a lynchet, accumulated due to early cultivation on the slope. The two-field extent of this field system is the surviving uppermost tip of a more extensive field system truncated by subsequent sinking of the Scillies' land mass and formerly occupying part of the shallow basin now submerged as Porth Morran. Other areas of broadly contemporary field system extend from the eastern upper shore of Porth Morran onto the central area of White Island, from 320m to the ESE and within sight of this monument across the present bay. A hut circle has also been identified below the present mean low water mark in northern Porth Morran and prehistoric flint artefacts have been recovered from the northern coastal cliff of Porth Morran, to the east of the field system in this monument. In its broader context, although this monument is located on what is now a fairly small uninhabited island, linked to the much larger St Martin's island at low tide, the physical environment in which its fields and cairn were originally constructed was a rocky promontory, facing a broad valley to the south, on the northern edge of the single large island that formerly united much of the area of the present Isles of Scilly archipelago, from St Mary's northwards. The gradual sinking of the land since this monument's features were constructed has led to the fragmentation of that island into the present scatter of large and small islands and rocks. Apart from the other related settlement remains on this island discussed above, broadly contemporary funerary cairns in the dispersed cairn group on northern White Island are located from 40m and 45m to the north east of the cairn in this monument.

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: 15395

Legacy System: RSM


Books and journals
Russell, V, Isles of Scilly Survey, (1980)
Thomas, C, Exploration of a Drowned Landscape, (1985)
Thomas, C, Exploration of a Drowned Landscape, (1985)
Thomas, C, Exploration of a Drowned Landscape, (1985)
Thomas, A C, 'Cornish Archaeology' in Recent Fieldwork in the Isles of Scilly, , Vol. 14, (1975), 87-94
consulted 1994, Thorpe, C., AM 107 for Scilly SMR entry PRN 7095, (1988)
consulted 1994, Thorpe, C., AM 107 for Scilly SMR entry PRN 7097, (1988)
consulted 1994, Thorpe, C., AM 107 for Scilly SMR entry PRN 7099, (1988)
consulted 1994, Thorpe, C., AM 107s for Scilly SMR entries PRN 7096-7, (1988)
North-west part. Consulted 1994, Thorpe, C., AM 107 for Scilly SMR entry PRN 7099.01, (1988)
Rees, S.E., AM7 scheduling documentation for CO 998, 1975, Cairn 'g'. Consulted 1994
Title: 1:10000 Ordnance Survey Map; SV 91 NW Source Date: 1980 Author: Publisher: Surveyor:
Title: 6": 1 mile Ordnance Survey Map; SV 91 NW Source Date: 1963 Author: Publisher: Surveyor:

End of official listing