Survey and Excavation at Henllys Top Field and Cwm Gloyne Enclosures

STUDIA CELTICA, XXXV (2001), 89–108 Survey and Excavation at Henllys Top Field and Cwm Gloyne Enclosures HAROLD MYTUM1 AND CHRIS WEBSTER2 Summary Geophysical survey and trial excavations at two enclosed settlements in north Pembrokeshire revealed evidence of internal occupation with earth-fast timber build- ings. Whilst closely datable artefacts were absent, radiocarbon dating suggests occupation at Henllys Top Field in the late Iron Age to Roman period, and at Cwm Gloyne in the Roman or post-Roman period. Neither site produced Roman pottery, despite their proximity to Castell Henllys from which a wide range of Roman artefacts has been recovered. This suggests that Roman material was not widely available in the region and that Castell Henllys had unusual differential access to Roman goods, probably to be asso- ciated with its higher status. Introduction The survey and partial excavation of a ploughed-out defended enclosure at Henllys Top Field and two adjacent inland promontory forts at Cwm Gloyne formed part of a more extensive project of survey and excavation around the extensively excavated site of Castell Henllys (Mytum 1999). The programme comprised excavation at Berry Hill Camp (Mytum and Webster 1993), field survey at Carnalw (Mytum and Webster 1989), geophysical surveys at Castell Mawr, Caerau and Caer, Bayvil (Mytum and Webster 2001) and the excavations reported here. Details of the focus of the research have been given previously (Mytum and Webster 1993) but the primary aims were to place Castell Henllys in the local settlement hierarchy and to assess the uniqueness of the large amounts of Roman pottery found there. Topography The sites of Henllys Top Field and Cwm Gloyne lie about 5km from the north coast of Pembrokeshire in the river system of the Afon Nyfer, which enters the sea at Newport. Geologically, the area is formed of Ordovician shales that produce a dissected landscape 1 University of York. 2 Somerset County Council Sites and Monuments Record. 90 HAROLD MYTUM AND CHRIS WEBSTER FIGURE 1. The location of Castell Henllys, Henllys Top Field, Cwm Gloyne and other enclosures in the area. of low, rolling hills separated by deep valleys. The hills rise, typically, to about 200m and slope with a convex profile into the valleys, which are narrow and steep-sided at the bottom. Henllys Top Field lies at about 140m just below the crest of a ridge above the valleys of Cwm Gloyne and Nant Duad. This location is typical of many enclosures in south-west Wales (Crossley 1963), and excavations on such sites have produced dates in the Iron Age or Romano-British periods (Williams 1988). The twin sites of Cwm Gloyne lie at about 110m at the top of the steep valley side of Cwm Gloyne. Here a promontory has been formed by erosion by a subsidiary stream and which a shallow valley further divides. To the north the ground is level but on the other three sides it falls extremely steeply into the valleys below. Again this situation is typical of a number of sites in north Pembrokeshire, including that of Castell Henllys itself, which lies about 1.5km to the east above the next tributary of the Afon Nyfer. SURVEY AND EXCAVATION AT HENLLYS TOP FIELD AND CWM GLOYNE 91 FIGURE 2. Henllys Top Field, showing relationship to Castell Henllys and field boundaries shown on 1775 map (left) and location of the excavation trenches and the ditch plotted from aerial photographs (right). Henllys Top Field The site is not visible on the ground but was discovered in 1984 by Michael Freeman (then of Pembrokeshire Museum Service) on vertical air photographs taken in 1955 by Meridian Airmaps and now in the Dyfed County Record Office (Ref. HDX/672 Box 210 230 Sheet 12155). The crop mark showed as a roughly circular enclosure surrounding the junction of three field boundaries. The excavation at Easter 1986 was designed to sample the interior of the enclosure with a system of linear trenches, to assess the extent of plough-damage and the nature of any surviving evidence. One of the field boundaries shown on the 1955 aerial photograph had been removed so the site was roughly located by measurement along the surviving field boundary. Resistivity equipment was then used to pinpoint the location of the ditches. Initially the trenches (Figure 2) were dug by hand, as the site of Walesland Rath had produced a large proportion of its finds from the topsoil (Wainwright 1971). No artefacts were recovered from the ploughsoil in trenches I–III and so a machine was used to remove this from the extension to trench III and all of trench IV. Trench I was located parallel to the field bank and crossed the ditch on the western side of the enclosure. It was evident that plough-damage was severe in this area and no features other than the ditch were observed cut into the rock that lay immediately beneath the plough-soil. Trench II was opened along the same line as trench I to cross the eastern side of the enclosure. This located not only the ditch itself but also several features close to the ditch, inside the enclosure. Trench III was opened running at right angles to the other two, out from the field boundary, towards the enclosure ditch on the northern side. Plough-damage was again evident and only the base of one post-hole 92 HAROLD MYTUM AND CHRIS WEBSTER FIGURE 3. Henllys Top Field, plan of features in Trench IV. SURVEY AND EXCAVATION AT HENLLYS TOP FIELD AND CWM GLOYNE 93 was preserved. The results of this preliminary work were sufficiently promising to merit extension of the excavations by machine. Trench III was extended to locate the position of the enclosure ditch on the north, but most effort was directed towards trench IV, a northerly extension from trench II (Figure 3). This area was selected because of the survival of features in this area of the site protected by deeper soil. An area 20m by 8m was stripped to the base of the plough-soil. The enclosure Profiles of the ditch were fully excavated in trenches I and II and its course recorded in plan in trenches III and IV. The ditch was V-shaped and survived to a depth of 0.5m below the base of the ploughsoil. The width varied from 1.5m in trench I to over 3m in trench IV; the difference was presumably caused by differing degrees of erosion. The ditch in trench I on the western side of the enclosure seems to have silted natu- rally with no evidence for any recutting. The lower portion of the ditch on the oppo- site side of the site in trench II showed a similar natural filling but the top of the ditch was composed of a less silty material containing patches of charcoal and two late-nineteenth-century sherds (finds 4, 5). This may be interpreted as deliberate filling of the ditch, with what remained of the bank, in the course of agricultural improvement. The charcoal in the top layer of the ditch suggests that a hedge or scrub on the bank had been burnt off before the levelling operation began. Where the enclosure ditch crossed trench IV it was seen as two straight sections but its overall shape, judged from the aerial photograph, is an oval some 67m by 53m enclos- ing an area of about 0.28ha. Nothing survived of the bank in the excavated area but differences in plough-damage to the bedrock may have indicated a width of c.2.5m. Using this figure, the enclosed area would be c.0.23ha. The position of the entrance is not clear from the aerial photograph and was not located within the excavation. The interior The majority of evidence for features in the interior came from trench IV; plough-damage being severe elsewhere. All the features were seen only where they cut into the bedrock, with the exception of one layer (35) that was observed as a thin spread of dark earth in the south-west of the trench. The northern edge was clear, as the layer occu- pied a shallow hollow, but to the south it thinned and became more mixed with ploughsoil, confusing its southern boundary. It is possible that the northern edge of the layer indicates the line of the rear of the destroyed bank that had protected the bedrock to the north in the earlier phases of ploughing. This area of bedrock was still closer to the surface than others as could be seen from recent ploughscars. The mixed nature of layer 35, the finds (which included nineteenth-century sherds) and the lack of any features showing at this level indicates that it has been disturbed by ploughing. The features beneath layer 35 consisted of post-holes, stake-holes, irregular scoops and areas of burning. To the west was an area of small, shallow post- and stake-holes that formed no obvious pattern. To the south and east the features were generally larg- er; five deeper post-holes (12, 17, 31, 42, 71) were excavated, of which two (17, 31) had extended into shallower, sloping areas perhaps as a consequence of the post being dug 94 HAROLD MYTUM AND CHRIS WEBSTER FIGURE 4. Details of features. Sections of 36 and 61 at Henllys Top Field, plan and section of 78 at Cwm Gloyne. out. Four post-holes (12, 17, 18, 31) contained appreciable quantities of charcoal and burnt, heat-shattered rock. Further evidence for fires in the area came from two areas (5, 32) where the bedrock had been reddened by heat.

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