Gwynedd Archaeological Trust
Regional Historic Environment Record

Castell Promontory Fort, Near Trefadog

Primary Reference Number (PRN) : 1
Trust : Gwynedd
Community : Llanfaethlu
Unitary authority : Ynys Mon
NGR : SH29108590
Site Type (preferred type first) : Early Medieval PROMONTORY FORT
Status : Scheduled Ancient Monument

Summary :
A heavily defended promontory on the north west coast of Anglesey, now protected as an ancient monument of national importance. The site was excavated by D. Longley in 1984-5 and was found to consist of a massive defensive bank and ditch on the landward side, enclosing an area of some 250 square metres. The foundations of a large 14th century house were revealed within the enclosure, which was later used as a metal working site. Finds included a bronze fastener, metal working debris and a single sherd of samian pottery.

Description :
Small natural promontory with sea on two sides, fortified on land side with large ditch and bank. (RCAHMW, 1937)

No trace of entrance, which must have been destroyed by erosion of internal structures. <2>

Published 25 in survey revised. <3>

As described. <4>

Prior to excavation the site presented the appearance of a natural knoll of boulder clay bounded by a steep sea cliff to the NW and NE and by a bank and external ditch on the landward sides, the whole constituting a small defended promontory of around 250 sq metres within the defences.

An area of approximately 245 sq metres was excavated across the defences and interior. It became clear that the appearance of a knoll had been created by the erosion of bank material into the interior from a considerably more massive defence that had been anticipated, and that the original character of the site would have comprised a level promontory defended by a bank, now surviving to a height of 2m, inside a ditch 13m wide and 4m deep. The scale of defence is disproportionately massive to the small area of the interior surviving although it was established that at least some of the NW interior had been lost through erosion of the cliff face. In this connexion, however, it is noteworthy that the rampart terminated in advance of the cliff edge.

The rampart displayed some complexity in its make up initially comprising a turf bank capped by clay and rounded beach pebbles, and finally, by boulder clay quarried from the ditch. No earth-fast revetment for the bank was recognised although the inclination of material in its make up suggested that some external support would originally have been provided, and there is a strong indication that the front of the bank has been eroded into the ditch.

This defence superseded an earlier demarcation represented by a palisade slot continued to the present cliff edge beyond the termination of the rampart. Within the enclosure a large rectangular structure with markedly rounded corners was identified, aligned NE-SW and measuring 10.8m x 5m with stone-faced and clay-cored walls over 1.2m thick. The SW wall in the lee of the rampart survives to a height in excess of 1m, although elsewhere stone robbing and erosion of the cliff face had taken their toll.

The building was provided with a circular stone-set hearth at its SW end and a complex arrangement of drains. After the structure had fallen into disrepair the promontory became the scene of metalworking on a limited scale with a number of hearths dug through the floor of the now dilapidated building. Very few diagnostic artefacts were recovered during the course of the excavation although radiocarbon and remnant magnetic determinations may aid the establishment of a chronological sequence for the site.

Notable finds include a small bronze fastener, debris from the process of metal working and a samian sherd sealed by collapse of the rectangular structure.

It is an unfortunate postscript to the history of the site that the area of metalworking activity has been the focus for illicit excavation in recent times with its attendant disturbance of the stratigraphy. <5>

The site is as described, but is overgrown and the western bank is suffering erosion. (Davidson & Jones, 1997)

Medieval. Not visited. (Smith, 2005)

Sources :
Davidson, A. & Jones, S. , 1997 , Coastal Erosion Survey: Anglesey ( © GAT)
Smith, G. , 2003 , Prehistoric Defended Enclosures: Scoping for Pan-Wales Assessment ( © GAT)
Smith, G. , 2005 , A Survey of Prehistoric Defended Enclosures in North West Wales 2004-2005: West Conwy, Gwynedd (Arfon) & Anglesey ( © GAT)
Smith, G. , 2008 , Iron Age Settlements in Wales: Cadw Defended Enclosures Publication Hillforts and Hut Groups in North-West Wales ( © GAT)
The Royal Commission on the Ancient and Historical Monuments of Wales , 1937 , An Inventory of the Ancient Monuments in Anglesey
Waddington, K. , 2010 , Early Celtic Societies in North Wales
Waddington, K. , 2013 , The Settlements of Northwest Wales: From the Late Bronze Age to the Early Medieval Period
Ordnance Survey , 1969 , SH28NE 1 , <2>
Ordnance Survey , 1969 , 25" Map , <3>
Carruthers, I. , 1984 , PRN01 , <4>
Longley, D. , 1984 , Archaeology in Wales , <5>
Royal Commission on Ancient and Historic Monuments , 1983 , PRN 01 , <6>
Longley, D. , 1991 , Medieval Archaeology , <7>
Cathcart King, D. J. , 1983 , Castellarium Anglicanum , <9>

Events :
40781 : Excavations at Castell, Trefadog (year : 1984)
40362 : Coastal Erosion Survey: Anglesey (year : 1997)
40621 : Prehistoric Defended Enclosures in North-west Wales, 2004-5: West Conwy, Gwynedd (Arfon) and Anglesey (year : 2005)
44557 : Early Celtic Societies in North Wales (year : 2010)
45042 : Iron Age Settlements in Wales: Cadw Defended Enclosures Publication. Hillforts and Hut Groups in North-West Wales. (year : 2008)
40620 : Prehistoric Defended Enclosures: Scoping for Pan-Wales Assessment (year : 2003)

Related PRNs : 95571

Compiled date : 25-09-1986


The above data are supplied by GAT in partnership with its Local Authorities (Anglesey, Conwy and Gwynedd County Councils, and Snowdonia National Park Authority), © GAT 2018 (and in part © Crown, 2018 - as indicated)
This information is supplied for the purposes of personal interest only and may not be used as part of a commercial project.

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