Prehistoric entrance grave and regular field system on north western Porth Hellick Down, St Mary's


Heritage Category: Scheduled Monument

List Entry Number: 1011950

Date first listed: 09-Oct-1981

Date of most recent amendment: 11-May-1995


Ordnance survey map of Prehistoric entrance grave and regular field system on north western Porth Hellick Down, 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 92838 10876

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.

Entrance graves are funerary and ritual monuments whose construction and use dates to the later Neolithic, Early and Middle Bronze Age (c.2500 - 1000 BC). They were constructed with a roughly circular mound of heaped rubble and earth, up to 25m in diameter, whose perimeter may be defined by a kerb of edge-set slabs or, occasionally, coursed stone. The mound contains a rectangular chamber built of edge-set slabs, coursed walling or both, and covered by large slabs, called capstones, set transversely across the chamber. The chamber was accessible via a gap in the mound's kerb or outer edge and often extends back beyond the centre of the mound. The cairn's mound and chamber may incorporate natural boulders and outcrops. Excavations in entrance graves have revealed cremated human bone and funerary urns, usually within the chambers but on occasion within the mound. Unburnt human bone has also been recovered but is only rarely preserved. Some chambers have also produced ritual deposits of domestic midden debris, including dark earth typical of the surface soil found within settlements, animal bone and artefact fragments. Entrance graves may occur as single monuments or in small or large groups, often being associated with other cairn types in cemeteries. They may also occur in close proximity to broadly contemporary field boundaries. The national distribution of entrance graves is heavily weighted towards the Isles of Scilly which contain 79 of the 93 surviving examples recorded nationally, the remaining 14 being located in western Cornwall. Regular 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 defined by boundaries laid out in a consistent manner, along two dominant axes at approximate right angles to each other. This results in rectilinear fields which may vary in their size and length-width ratio both within and between individual field systems. The fields are bounded by rubble walls or banks, often incorporating edge- or end-set slabs called orthostats. Within its total area, a regular field system may be subdivided into blocks differing in the orientations of their dominant axes. Regular field systems may be associated with broadly contemporary settlement sites such as stone hut circles. Some regular 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, regular field systems form a substantial proportion of the 71 surviving areas of prehistoric field systems recorded on the Isles of Scilly. The variations in form, longevity and the associations of both entrance graves and regular field systems combine to provide significant insights into the physical and social organisation of past landscapes and the diversity of beliefs and burial practices among prehistoric communities.

This entrance grave and the adjacent regular field system on Porth Hellick Down have survived well. The entrance grave is one of the largest examples known and contains a very full range of the features pertaining to this class of monument. It also retains several unusual features, including the outer platform, the angled junction between the chamber and passage, the blocking slab at that junction, and the buttressed terminal slab. The excavations by Bonsor left the mound and platform substantially intact and the high quality of his records, themselves important in the history of archaeological technique, have enhanced our knowledge of the structure of this entrance grave, despite the earlier clearance of the passage and chamber during an unrecorded antiquarian episode. The proximity of this large and complex entrance grave to the other smaller entrance graves and cairns on Porth Hellick Down demonstrates well the diversity and organisation of funerary practices during the Bronze Age. The close physical association between this cairn cemetery and the prehistoric regular field system contained within this monument illustrates the relationship between agricultural and funerary activity and the organisation of land use among prehistoric communities.


The monument includes a large prehistoric entrance grave and an adjacent prehistoric regular field system situated on the north western side of Porth Hellick Down, on south east St Mary's in the Isles of Scilly.

The entrance grave is located on the crest of the north western slope of Porth Hellick Down. It survives with a low, circular, level outer platform of turf-covered rubble, 21m in diameter, whose outer edge has a slight gentle slope descending 0.2m over its peripheral 2m. Centred within this platform is a sub-circular earth and rubble mound, up to 12.25m in diameter. The mound has near vertical edges, up to 0.8m high, retained by a kerb of slab-built walling, 2-3 courses high, and incorporating some edge-set slabs. The kerb is laid out in short straight lengths around the mound's north east half, giving that half a slightly facetted plan, but around the south west half it adopts a more smoothly curved course. Within the kerb, the shallow-domed upper surface of the mound rises to 1.6m high. Slightly east of the mound's centre is a sub-rectangular slab-built funerary chamber, set at an angle to a passage linking it with the north west edge of the mound. The floor of the passage and chamber remain at ground level, such that the top of the chamber's covering slabs lie beneath only a thin turf at the top of the mound.

The chamber's interior measures 3.5m along its NNW-SSE long axis by up to 1.5m wide and 1m high. The sides have a lower course of large edge-set slabs with smaller slabs laid above them to raise and level the chamber's covering slabs. The SSE end is closed by a single edge-set slab. The chamber is spanned transversely by four large slabs, called capstones, up to 2.5m long and 1.25m wide, laid edge to edge. In plan, the chamber is D-shaped, its WSW side almost straight while its ENE side is convex relative to the interior. At the outer, NNW, end of the chamber both sides are angled westwards to join the inner end of the passage. The passage, with a NW-SE long axis, measures 4m long by 0.9m wide and 1m high and is unroofed, extending from the north west sector of the mound's kerb to the outer end of the chamber. The sides of the passage are built of coursed rubble incorporating edge-set slabs. The junction between the passage and the chamber is marked by a tranverse slab, 0.9m high and 0.75m wide, almost blocking the passage, leaving a gap only 0.25m wide beside its south west edge. Where the outer end of the passage meets the mound's kerb, the passage width is again constricted, to 0.7m wide, by an edge-set slab jutting into the passage from the south west side.

In addition to the surviving physical remains, partial excavations at this entrance grave in 1899 by the archaeologist George Bonsor revealed further information about this entrance grave. His surviving records and the photographs of his excavations, the first to be recorded in detail on Scilly, revealed a kerb of contiguous slabs along the outer edge of the mound's surrounding platform. He also confirmed the presence of, and exposed, the outer face of the mound's kerb. His examination of the floor deposits within the passage and chamber, already exposed by an unrecorded antiquarian excavation, revealed fragments of decorated Bronze Age pottery and a piece of pumice stone. He exposed the full extent of the chamber capstones and his excavation behind the chamber's terminal slab revealed a rubble buttress, recording these structural details on meticulously drawn plans and sections. This entrance grave, one of the largest examples of its class, was subsequently partly restored for public presentation by the Ministry of Works, re-covering the chamber with turf, removing the platform's outer kerb and slightly modifying the mound's outer kerb.

From 20m beyond this entrance grave's WNW perimeter, the rubble walls of a prehistoric regular field system extend up the north western slope of the Down, above the limit of the modern enclosure walls. The prehistoric field system is largely masked to close inspection by extensive modern scrub-cover but its heaped rubble walls, up to 2m wide and 0.3m high, appear where crossed by modern tracks and clearings, while the field system's broader layout has been observed under low winter sunlight. This evidence indicates the field system's survival over 3.6ha along the north western slope of the Down, continuing across the adjacent saddle of the Normandy Gap and Water Rocks Down to the north east. The constituent plot-walls are predominantly orientated along two axes at right angles to each other, north west-south east and north east-south west, denoting a regular pattern of rectilinear fields; the distances between successive field walls crossed by modern tracks suggest length-width dimensions in the range 20m-50m for the prehistoric fields. The entrance grave in this monument is the largest and northernmost example in a cairn cemetery containing at least eight other cairns dispersed across the central plateau of Porth Hellick Down. The cairns in this cemetery vary in form but at least six are entrance graves, forming one of the largest surviving groupings of this type of monument. Other prehistoric cairn cemeteries, including entrance graves, are located on the adjacent coastal downs of Salakee Down to the south west and Normandy Down to the NNE. The entrance grave and the land immediately surrounding it are in the guardianship of the Secretary of State.

The English Heritage direction signs and posts, stanchion-and-wire fence, stile, information plinth and plaque, concrete boundary markers and laid gravel surface in the passage and chamber of the entrance grave are excluded from the scheduling but the ground beneath them is included.

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: 15367

Legacy System: RSM


Books and journals
Ashbee, P, Ancient Scilly, (1974)
Ashbee, P, Ancient Scilly, (1974)
Ashbee, P, Ancient Scilly, (1974)
O'Neil, BH St J, Ancient Monuments of the Isles of Scilly, (1949)
Russell, V, Isles of Scilly Survey, (1980)
Thomas, C, Exploration of a Drowned Landscape, (1985)
Ashbee, P, 'Cornish Studies' in George Bonsor: An Archaeological Pioneer From Spain On Scilly, , Vol. 8 (1980), (1981), 53-62
consulted 1994, Waters, A., AM 107 for Scilly SMR entry PRN 7527, (1988)
consulted 1994, Waters, A., AM 107 for Scilly SMR entry PRN 7528, (1988)
consulted 1994, Waters, A., AM 107 for Scilly SMR entry PRN 7528.01, (1988)
DoE/HBMC, Ancient Monuments Terrier for Porth Hellick Down Burial Chamber, (1984)
Title: 1:2500 Ordnance Survey Map; SV 9210 Source Date: 1980 Author: Publisher: Surveyor:
Title: 1:2500 Ordnance Survey Map; SV 9210-9211 Source Date: 1980 Author: Publisher: Surveyor:

End of official listing