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

A Scheduled Monument in St. Martin's, Isles of Scilly

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Latitude: 49.9781 / 49°58'41"N

Longitude: -6.2944 / 6°17'39"W

OS Eastings: 92226.547265

OS Northings: 17496.224308

OS Grid: SV922174

Mapcode National: GBR BXVR.1MZ

Mapcode Global: VGYBR.VT76

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

Scheduled Date: 7 October 1976

Last Amended: 20 February 1995

Source: Historic England

Source ID: 1010161

English Heritage Legacy ID: 15395

County: Isles of Scilly

Civil Parish: St. Martin's

Traditional County: Cornwall

Lieutenancy Area (Ceremonial County): Cornwall

Church of England Parish: Isles of Scilly

Church of England Diocese: Truro


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
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.

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.

Source: Historic England

Reasons for Scheduling

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'
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
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.

Source: Historic England


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

Title: 6": 1 mile Ordnance Survey Map; SV 91 NW
Source Date: 1963

Source: Historic England

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