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.
Fogous are walled underground passages constructed during the later Iron Age
(about 400 BC to AD 50), though with evidence for their use continuing into
the Romano-British period, in at least some cases to the 2nd century AD. The
ground plan of fogous varies considerably but all include a drystone-walled
passage, the largest being 30m long and 2m wide, roofed by flat cover-slabs
and with an entrance at one or both ends. The few excavations of fogous have
shown that the walling was initially built and roofed in a trench which was
then backfilled. The passage is often curved or `S'-shaped and several
surviving examples include subsidiary passages or chambers whose entry from
the main passage may be constricted by a narrow creep passage. More than one
phase of construction is evident in some cases. Most surviving fogous
are located close to or within contemporary settlements, often courtyard house
settlements but also including embanked enclosed settlements called rounds.
Various suggestions have been offered for the functions of fogous, with
particular support for their interpretation as safe refuges during raids,
religious sanctuaries or cool storage areas for foodstuffs. At least twelve
fogous are known to survive nationally, with five other possible survivals.
Their national distribution is restricted to the far west of Cornwall, to
Penwith and around the upper Helford River, and with this single example on
the Isles of Scilly.
The fogou on northern Peninnis Head, 170m south of Carn Gwavel Farm survives
very well. Its presence on Scilly provides a significant extension of the
distribution of this monument class and is an important addition to the known
range of structural features pertaining to the latter part of the Iron Age on
the islands. Despite some collapse of the original entrance passage as evident
through the creep, and two very minor roof falls in the accessible inner
passage, this fogou is one of very few whose built structure and original
deposits will remain almost intact and unexcavated. Consequently it is of
considerable significance for the study of this enigmatic class of monument
and its role in the lives of the later prehistoric and Romano-British
communities in the far south west of England.
Details
The monument includes an Iron Age to Romano-British underground walled passage
called a fogou, situated on a north easterly midslope at the northern end of
Peninnis Head on St Mary's in the Isles of Scilly.
The fogou survives with an underground chamber-like passage measuring 4.97m
long, north east-south west, by up to 1.18m wide and 1.18m high. Limited roof
collapse near the north east end of passage reveals that the top of its cover-
slabs at that point lie 0.4m-0.48m beneath the present ground surface. Its
floor remains roughly level but in plan the passage undergoes a shallow `S'
curve throughout its length, terminating in the south west at an oblique
narrow end-wall, but closed by a broader transverse wall at the north east
end. At the foot of the north east end-wall, on its south east side, is a very
low narrow opening covered by a large lintel slab. This opening, called a
creep, formed the original constricted point of entry into the passage, which
comprised the innermost chamber of the fogou. The creep, 0.57m wide by 0.27m
high, is visible for up to 1.36m before becoming wholly blocked by collapsed
debris. Shortly before that blocking, the creep widens on its north west side
and is considered to extend further as the fogou's original entrance from the
ground surface.
The passage is walled by granite slabs, generally 0.2m to 0.5m across, laid in
five to seven rough courses; the base of the wall also includes three
relatively small edge-set slabs, to 0.4m high: two adjacent at the south west
end and one nearby in the south east wall. The larger spaces between wall
slabs are frequently infilled by small pebbles and the local subsoil, called
ram, which is considered to have been applied deliberately as a mortar, a
practice known from prehistoric stone-built monuments elsewhere on Scilly. At
their upper levels, the passage walls curve gently inwards as each course of
slabs projects slightly beyond that immediately beneath, a technique known as
corbelling. The lower masonry of the passage's south east side-wall continues
into the creep without any joint, confirming that the creep and the passage
are of one build.
The passage is roofed by five large cover-slabs laid flat across the top of
the walls and ranging from 0.47m to 0.86m wide. The central cover slab and
that to its north east almost touch, but gaps 0.25m-0.37m wide separate the
others. The gaps separating the south western and north eastern cover slabs
from those adjacent to them are infilled by small boulders and rubble: it was
limited collapse of this infill in the north eastern gap in May 2000 that led
to the discovery of the fogou and created the present aperture by which the
passage has been examined. By contrast, the space between the central cover
slab and that to its south west is closed by a row of smaller slabs laid
neatly across the gap from above; this is a later modification following a
previous and unrecorded collapse of the gap's rubble infill which produced a
mound of soil and silt, with loose slabs along its southern edge, on the
passage floor directly beneath the gap.
Beyond the soil mound and rubble from that previous collapse, the earth floor
of the passage combines patches both of subsoil and dark ploughsoil, the
result of silts filtered through the roof and wall, and some recent
contamination by visitors examining the passage. However, in the absence of
evident excavation or other disturbance to that surface, any stratified floor
deposits pertaining to original activity within the passage will survive
intact beneath the visible surface.
Beyond this monument, there is evidence for settlement and ritual activity in
the surrounding area both before and after the period of fogou construction.
Funerary cairns dating to the Bronze Age survive on high ground at both ends
of the broad headland of Peninnis Head, the nearest being situated only 185m
north west of this monument, while Middle to Late Bronze Age settlement sites
are exposed along the western coastal cliff of Peninnis Head, with prehistoric
field systems surviving further south around the flanks of the headland. These
form the subject of separate schedulings. Evidence from the Roman period
includes stone artefacts found nearby in the Hughtown area during the 19th
century, an altar stone and several column fragments, showing the likely
presence there of a Romano-Celtic temple.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
It includes a 5 metre boundary around the archaeological features,
considered to be essential for the monument's support and preservation.
