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 field system in Green Bay survives well, clearly displaying the character
of the prehistoric land division and its manner of execution. Its extensive
survival well into the inter-tidal zone, despite rising sea levels, confirms
its long term stability against a considerable period of submergence. It
complements the prehistoric field system and settlement survivals at various
levels around southern Bryher to provide an unusually complete view of
prehistoric land allotment across the altitude range into the now-submerged
zone. Consequently this field system is important for the study of prehistoric
land-use responses to island environments, given chronological depth in this
monument by the evidence for later modification of the walling pattern and by
the presence of the Romano-British funerary cist. The proximity of the field
system to the cairn cemetery on Samson Hill also demonstrates the relationship
between farming, funerary and ritual activities among the prehistoric
communities that used this monument. Although subject to some disturbance of
its upper levels by wave action, the Romano-British cist provides a rare
illustration of land use in this now submerged zone during that later period;
its excavation has confirmed its construction and type, while leaving its
structure in place. The resulting close dating of this cist has made a
valuable contribution to studies of the rate of submergence of the islands'
land mass.
Details
The monument includes a prehistoric field system in the inter-tidal zone of
Green Bay on the east coast of Bryher in the Isles of Scilly. Slightly beyond
the southern end of the field system's known extent is a Romano-British
funerary cist.
The field system is defined by rubble walls generally 0.5m wide, most being
partly masked by surrounding sand and pebble overburden on the middle shore.
The walls incorporate almost continuous rows of edge- and end-set slabs
averaging 0.3m high but including occasional large boulders. One prominent
wall in the north west of the field system differs in containing much larger
end-set slabs, to 0.8m high and spaced 0.5m-1m apart.
The field system's walls define a pattern of small rectilinear plots, 10m-20m
across, bounded by straight or slightly sinuous walls; the axis of their side
walls changes from being predominantly north west - south east in the northern
sector to WSW-ENE near the centre of the scheduling and returning to almost
east-west at the south. Passing through the northern plots are two more
sinuous parallel walls, generally 7m apart, running NNE-SSW with traces of a
third wall on the same axis 7m east of their visible northern end. These walls
are considered to derive from a later prehistoric modification of the field
system, resulting in the removal of slabs for their fabric from nearby lengths
of the rectilinear plot walls. Towards the centre of the scheduling the
longest visible length of the parallel walls curves towards the south.
Increasing sand and shingle overburden mantles the southern half of the
scheduling masking finer detail from view in that sector; however, 15m south
from the east end of the southernmost visible east-west wall are remains of a
box-like funerary structure called a cist whose upper edges are exposed on the
middle shore. It is of a Romano-British form known as a Porthcressa-type cist,
datable to the first to fourth centuries AD and named after a site on St
Mary's, Scilly, where their characteristic features were first fully defined.
Its visible remains include a setting of small slabs defining an oblong
internal area 1.8m long, north-south, by up to 0.9m wide, infilled to within
0.2m of its side slabs by shore sand. Its defining slabs are generally 0.3m-
0.5m long, projecting to 0.2m from the surrounding sand. They include a row of
three slabs along the west side, a cluster of at least three slabs across the
rounded north end, much encrusted by seaweed, and two slabs across the south
end. At least two more slabs survive on the east side but leave a gap to the
southern end. These visible remains have clearly been subject to some surface
disturbance by wave action and all lower slabs are masked by shore sand. The
fuller sub-surface details of the cist were revealed by excavation in the
1970s, confirming the identification as a Porthcressa-type cist. The
excavation showed that the cist is ovoid, 1.37m long by 0.76m wide internally.
It had been built in a pit dug through the old land surface into the subsoil;
its northern end is pointed, defined by edge-set slabs, while the southern end
is walled by coursed slab walling. The cist is floored by small laid slabs,
unique among known examples of this cist type.
Beyond this scheduling, further broadly contemporary field system remains are
exposed at a similar inter-tidal level at the northern and southern ends of
Green Bay, 200m to the north east and to the south east respectively, with
prehistoric settlement sites situated close to the southern remains. These
inter-tidal remains on the south east coast of Bryher are complemented on the
south west coast by another prehistoric field system and settlement surviving
in the inter-tidal zone of Great Porth and extending over the Heathy Hill
promontory. On the higher land of Samson Hill, overlooking this scheduling
from the south, a prehistoric cairn cemetery is dispersed about the summit
area. All of these archaeological features are the subjects of separate
schedulings.
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.
