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.
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 one of the
three principal forms of prehistoric field system, along with irregular field
systems and some groups of prehistoric linear boundaries, which survive in
over 70 areas of the Isles of Scilly. They provide significant insights into
the physical and social organisation of past landscapes and they provide
evidence for the wider contemporary context within which other nationally
important monuments were constructed.
The prehistoric field system in southern Pentle Bay survives reasonably well,
displaying its manner of layout and construction; its three lengths of paired
walling form an unusual feature. Despite intermittent exposure due to periodic
and shifting sandbanks, successive records of this field system have
demonstrated its extensive survival well into and beyond the inter-tidal zone,
confirming its overall stability against a considerable period of submergence
and providing information on the nature of early landuse in the lower lying
terrain of the prehistoric landscape which now lies below the high water mark.
Its value for the study of early landscapes is increased by the survival
nearby of the other prehistoric field system and settlement sites along the
southern and south western coasts of Tresco, giving the wider landuse context
broadly contemporary with the remains in this scheduling.
Details
The monument includes a prehistoric field system on the southern shores of
Pentle Bay on the south east coast of Tresco in the Isles of Scilly. The field
system contains a prehistoric corn-milling stone called a saddle quern. Where
exposed on the middle and lower shore, the field system walls are visible as
rows of closely spaced or continuous small slabs, frequently set on edge and
generally 0.2m-0.5m long by 0.2m-0.4m high, but reaching 1m long and 0.5m high
in places. In some sectors the walling acts as a slight breakwater, trapping
aggregations of water-borne rubble alongside. The field system's full extent,
known from successive surface surveys, is not normally visible at any one time
due to intermittent masking by shifting sandbanks.
The accumulated records show the overall field system revealed as exposures of
prehistoric walling on the very gently shelving middle and lower shore around
the west, north and east of Skirt Island, a rocky outcrop linked to Tresco by
dunes and defining the southern end of Pentle Bay. Wall exposures are recorded
up to 160m from Skirt Island on the north west and north, to 140m on the north
east and to 80m from it on the east and ESE. A short length of wall visible in
the northern face of the sand dune extending WSW from Skirt Island is also
considered to derive from this field system. In that overall area the walling
displays a rectilinear pattern with boundaries approximately 20m-45m apart on
north east-south west and north west-south east axes. At three locations
within its extent there are pairs of closely-spaced walls, 4m-8m apart, near-
parallel and with almost straight courses exposed variously over 10m-20m
lengths, deriving from former trackways and narrow enclosures incorporated in
the field system. Two such paired walls occur approximately 75m west and north
west of Skirt Island respectively and follow NNW-SSE courses; the third, with
a south west-north east axis, is approximately 50m ESE of Skirt Island.
Between the paired walling to the west of the Island, and towards their
southern end, a prehistoric saddle quern is visible as a granite slab 0.6m
long, 0.45m wide and 0.2m high, with a hollowed and smoothed upper surface on
which grain was ground. Located 5m north east of that same pair of walls is a
small rubble mound, 2.5m in diameter and 0.2m high, called a clearance cairn
and resulting from prehistoric field clearance.
Beyond this scheduling, prehistoric field systems and habitation sites survive
at several locations on the southern and south west shores of Tresco.
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.
