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CAERFAI, PROMONTORY FORT;PENPLEIDIAU PROMONTORY FORT

Site Details

© Copyright and database right 2020. All rights reserved. Ordnance Survey licence number 0100022206

NPRN 305396

Map Reference SM72SE

Grid Reference SM76282398

Unitary (Local) Authority Pembrokeshire

Old County Pembrokeshire

Community St Davids and the Cathedral Close

Type of Site PROMONTORY FORT

Broad Class DEFENCE

Period Roman, Iron Age

Site Description 1. Caerfai Promontory Fort consists of a crescent of three to four lines of banks and ditches, about 100m in length, having what appears to be a former entrance gap, about 30m across, on the east, blocked by two lesser banks, the whole set across the northern, landward approaches to a 45m wide neck of land that opens onto a roughly 100m east-west by 50m cliff-girt promontory; emplacements for circular structures have been reported but not confirmed in the interior and there is said to be a good natural, small-boat harbour to the south. (source OS 495 card; SM72SE9)

RCAHMW 2003.

2. DYFED ARCHAEOLOGICAL TRUST DESCRIPTION, 2010: Penpleidiau/Caerfai is a multivallate coastal promontory fort, naturally defended on by c.30m high sea cliffs to the west south and east. The northern side, approached across flat land, is defended by four substantial lines of bank and ditch c. 100m long. The defensive system is covered with bracken, brambles and gorse. The three inner lines of bank and ditch are close set with no berms between banks and ditch. The inner bank (1) stands 3m above the interior and 3.5m over the ditch on its outside. Its western end is above the vertical cliffs. Its eastern end terminates at the entrance. The second bank (2) is less substantial, standing just 2.5m above the ditches either side of it. It begins to turn slightly to the south at its western end before abruptly terminating at the cliff edge. At the entrance, (east end) bank 2 has a marked out-turn (to the north) and rises sharply to 3.5m high, dominating the entrance. Bank 3 is a similar size to bank 1, standing 3.5m above the flanking ditches. It terminates at its west end above the sea cliff. At the entrance the ditch on its outer (north) side curves around the terminal of this bank. The outer bank (4) is separated from the ditch on its inner (south) side by a c. 6m wide berm. This bank stand c. 3m above the ditch on its outer (north) side. Unlike the other three banks, bank 4 (and the ditch on its outer side) does not run up to the cliff edge at its western end but stops c. 45m short of it. A slighter continuation of this bank beyond its western terminal suggests that the builders had intended to continue the bank to the cliff edge, but did not complete. It is possible that the three inner banks were constructed as a single unit, with bank 4 and its ditch added later.

The entrance lies between the eastern end the banks and ditches and a steep coastal slope which runs down to the top of vertical sea cliffs. The two inner banks (1 and 2) continue to the south down steep coastal slope, albeit in a much reduced form - the inner bank (1) being just 1.2m high and bank 2 c. 0.5m high, with no obvious ditches. There is an obvious hollow on the north side of the slight inner bank (1) on the east side of the entrance. The entrance passageway through banks 1 and 2 is c. 4m wide. The ditch terminal outside bank 3 and bank 4 stop short of the edge of the coastal slope, forming a wide entrance area rather than a passageway.

The grass-covered interior slopes gently down from north to south and is rectangular c.100m N-S and 120m E-W. On the southwest, south and east sides the interior slopes down gently before ending in sea cliffs, indicating perhaps that not a great deal has been lost to erosion. However, on the northwest side a vertically-sided gully has removed a large portion (c.20%) of the interior as well as a little of the inner bank. It is clear that this gully must have formed after the fort's construction, otherwise the position of the defences makes no sense. This is one of the few coastal forts where it is possible to quantify loss, in the case of Penleidiau the 70m E-W and 40m N-S gully has formed since the Iron Age. It is also possible to demonstrate (with reference to the Ordnance Survey 1:2500 1st Edition map of and aerial photographs) that the eastern 15m of this gully opened up between 1880 and 1946. There was a little loss at the southwest end of the inner bank. The gully corresponds to a mineral rich band of shattered rock/geological fault, which the sea is exploiting. Post-medieval mining of the minerals has created a tunnel beneath the fort, no doubt exacerbating erosion. Indeed, it is possible that the gully did not begin to open up until the onset of mining. The character of the side of the gully indicates that it was formed by a series (six to seven) of catastrophic collapses, and that the interior will become an island detached from the defences following three more collapses.

Apart from the major loss caused by the gully there are few other problems associated with this fort. There has been loss above the high cliffs at the western end of the defences, but the banks here are covered with vegetation and apparently stable. Bank 2 is beginning to curve to the south at its western end as though to meet a cliff edge, and so loss here may have been only a few metres. Visitors following a path over the western end of the ramparts are causing some erosion, but this is not severe and is long standing, the path having been in use since the 1880s.

Penpleidiau is an unusual fort. It is rare for a coastal promontory fort to have four lines of banks and ditch, and where multivallation occurs normally the defences are designed to seen from the landward site, as at Porth-y-Rhaw and Greenala where the defensive banks rise one above the other to give the impression of impregnability. At Penplediau the flat landscape means that only the outer bank is visible, with the other banks hidden behind it. Only at the approach to the entrance are all four lines of bank and ditch readily apparent. If their purpose was to provide an impressive display as the entrance was approached then the Penplediau defences are adequate, and the termination of the outer bank short of the cliff top explained.

K Murphy, Dyfed Archaeological Trust, February 2010. PRN 2728.

Updated by T. Driver, RCAHMW, 2018.

© Crown: CHERISH PROJECT 2018. Produced with EU funds through the Ireland Wales Co-operation Programme 2014-2020. All material made freely available through the Open Government Licence.

3. A detailed magnetometry survey was conducted over approximately 2.5 ha of grassland and scrubland at Caerfai (Penpleidiau) by SUMO Services for the CHERISH Project in March 2019. No definite archaeological responses have been identified, though a large number of anomalies of uncertain origin have been mapped. The survey has identified a number of anomalies of uncertain origin. Sub-circular responses have been detected, and they may be a result of small enclosures, building platforms or ring-ditches. A possible trackway has also been mapped, along with several discrete anomalies of uncertain origin. Areas of enhanced magnetic response have been detected within the fort itself, and it is possible that these are archaeological or natural in origin. Evidence of a ploughing headland is also visible in the data, while one of the uncertain linear trends is possibly related to an historic field boundary.

Extract from Davies, R. 2019. Geophysical Survey Report 14719: CHERISH Ireland-Wales Project - Caerfai (Penpleidiau), Pembrokeshire. SUMO Services. Unpublished.

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