Ben Effrey Hillfort Excavation 2011 Data Structure Report By Tessa Poller Ben Effrey Excavations 2011 Table of Contents Summary Introduction Location and Background Aims Methodology Results Trench 1 Rampart 3 Rampart 2 Rampart 1 Topsoil Discussion Ramparts Conclusions Acknowledgements References Appendices i) Contexts ii) Small Finds iii) Drawings iv) Samples v) Photos List of Figures Figure 1 Locat ion Map of Hillforts in SERF area Figure 2 Hillshade model based on topographic survey of fort with location of trench Figure 3 View of Ben Effrey from lower slopes in the north west Figure 4 Aerial view of Ben Effrey from the north Figure 5 Views of BenEffrey Figure 6 Processed gradiometry results of the geophysical survey Figure 7 East facing section of ramparts and ditch Figure 8 Plan of trench showing ramparts Figure 9 Plan view of palisade showing stones at edge of trench; section view of palisade trench in Rampart 3 Figure 10 Plan view of dark ashy patch 1023 in ditch Figure 1 1 West facing section of ditch showing dark ashy concentration 1023 in centre of fill Figure 1 2 Massive boulders in south face of Rampart 2 (1010); slumped b oulder and compacted stones on face (1046) Figure 1 3 Line of stones 1045 between edges of Rampart 1, with core material 1016 in centre Figure 1 4 Vitrified fuel ash/ bog iron SF 7033 in core of Rampart 1 Figure 1 5 Views of Rampart 1 Figure 1 6 Rough stone surface north of Rampart 1 (1027) - 1 - Ben Effrey Excavations 2011 Summary Excavations at Ben Effrey hillfort took place between the 1st and 20th of August, 2011 as part of the Strathearn Environs and Royal Forteviot (SERF) project. A 30m by 2m wide trench was excavated over the remains of the ramparts on the south-east side the hillfort. The results of the excavation revealed the varied character of each of the three ramparts that define the south face of the fort. The outer rampart was built with earth quarried from an associated ditch and supported by a timber fence. The middle rampart had massive boulders at its foundation. While the innermost rampart showed signs of timber being interspersed between tightly knitted stones in its southern face. The different constructions may suggest more than on phase of building and perhaps indicates that each rampart had a distinct role. Introduction SERF has established a programme of investigating a number of hillforts surrounding the village of Forteviot. The primary aim of this programme is to obtain a relative chronological sequence of the hillforts within this landscape. On the northern slopes of the Ochils there is a notable concentration of sites classified as forts, of which we know very little. The results from the SERF programme so far have highlighted the value of systematic excavations in providing an overview of when these sites were constructed and how the fortifications were built. The fieldwork at Ben Effrey was the fifth season of work conducted through this programme. Figure 1: Location Map of Hillforts in SERF area: blue circles other forts excavated by SERF 2007- 2011, red circle Ben Effrey. Location and Background Ben Effrey is part of the Ochil Volcanic Formation, which generally consist of andesite and basalt lavas. This hill, like other areas around Craig Rossie, is also characterised by exposed rhyodacite. The superficial geology is mainly glacial tills and deposits of erratics situated in locally derived purple clay. - 2 - Ben Effrey Excavations 2011 During excavation the vegetation on the summit was predominantly short grass used as pasture for grazing sheep with heather and bilberry encroaching on the eastern and northern slopes. Ben Effrey is situated 350m above sea level, on the northern fringes of the Ochils. It has two summits with the hillfort located on the broader northern summit. Any views to or from the fort would have been obscured by the other summit to the southwest. Nonetheless, the easiest approach to hillfort on Ben Effrey is from a ridge to the southwest. The slopes in the other directions are much steeper with the western side defined by exposed bedrock and scree at its upper part, leading down to Pairney Burn. The character of the fort is much like Christison (1900) described over 100 years ago. The hillfort is defined by three parallel ramparts. From the stony western precipice, which is not enclosed, the ramparts curve clearly around the contours of the southern edge of the summit. Here large stones visibly protrude from the grass marking out the innermost and middle ramparts. Further east the slope steepens again. The ramparts are still visible but peter out towards the north east corner. Here the upper two ramparts seem to merge into less distinct terrace edges. However, on the north side of the hill the low remains of the innermost rampart can just be identified. The outermost rampart, a notable grass covered bank with slight ditch on the south side, becomes less clearly defined as it curves around to the east, here it no longer traces the base of the slope and becomes impossible to distinguish from rubble that has tumbled from higher upslope. Figure 2: Hillshade model based on topographic survey of fort with location of trench superimposed There is a break in the ramparts, defining a stone lined entrance, in the southeast. The stones lining the entrance appear to ride over the edge of the middle rampart. On the east side of the entrance the middle rampart widens, forming a small D-shaped area before it narrows again. Also to the east of the entrance a small circular platform appears to be cut into or abuts the outermost rampart. - 3 - Ben Effrey Excavations 2011 The interior of the fort, which measures roughly 60m by 35m, is undulating, but is fairly flat at its southern end. Although there are potential locations for structures such as roundhouses, no clear examples can be identified. Towards the north end the interior is more exposed and may have been less suitable for settlement. There is a modern walker’s cairn at this point. No previous archaeological investigations at Ben Effrey have been recorded. During the excavation a topographic survey was undertaken which recorded in more detail the topographic character of the fort (see Figure 2). Readings were surveyed approximately every 2m with a Leica 407 Total Station. Figure 3: View of Ben Effrey from lower slopes in the north west Figure 4: Aerial view of Ben Effrey from the north showing ridge to south east; sheep tracks mark the easiest route from the south - 4 - Ben Effrey Excavations 2011 Figure 5: Views of BenEffrey (top to bottom); from hillock to the south – showing Craig Rossie to the north and east of Ben Effrey; close up of ramparts from south; stone-lined entrance way to southeast. Pre-excavation Geophysical Survey (Figure 6) A gradiometric survey was undertaken by the author prior to excavation (Poller 2011). The results of this survey revealed strong magnetic responses of the ramparts on the south side of the hill, where they are more visible on the ground, with little magnetic indications of these features on the north or east sides. Each of the ramparts produced different responses: the innermost rampart (A) was the most continuous and had a strong positive magnetic signal with a halo of negative magnetism. The magnetic response of the middle rampart (B) was more discontinuous, characterised in several places, particularly to the east of the entrance, by strong dipolar readings. The magnetic response of the outer rampart is more subtle, with only one area (C) defined by a strong magnetic anomaly. At this point, a short segment of the ditch, running parallel to the inner rampart, was detected as a band of slightly negative response (E). Traces of a counterscarp (D) were also noted. Within the interior there was a general subtle magnetic response with few distinct anomalies. However, a possible site of human activity was identified as a rough circular area of variable magnetism located just inside the inner rampart (F). Outside the ramparts, on the south side of the hill, several isolated anomalies were detected and may be the location of igneous stones lying close to the surface. - 5 - Ben Effrey Excavations 2011 Figure 6: Processed gradiometry results of thef geophysical survey at Ben Effrey Aims The main purpose of the SERF excavation at Ben Effrey was to obtain a better understanding of the hillfort and to retrieve datable evidence of the main visible architectural elements. The long trench excavated across the ramparts was designed to sample of the defences of the site. The following research questions informed the excavation: o What is the nature and date of the ramparts? o How do the ramparts relate to one another? o How were the ramparts constructed? Are there evidence of reuse and/or recutting of the defences? o When did the fort fall out of use? Is there evidence of intentional demolition of the defences? o What are the conditions of archaeological deposits of the ramparts and ditches? How does the preservation compare to other areas on the site? Methodology The methodology employed at Ben Effrey was conducted in accordance with the Institute for Field Archaeologists Standard and Guidance for archaeological excavations (revised 2008). One long trench, measuring 30m by 2m, was excavated across the visible remains of the ramparts on the southeast side of the fort (Trench 1) (see Figure 2). The trench was deturfed and excavated by hand. According to standard practice, each context was fully recorded by photograph, drawing and written description. Artefact locations were recorded three-dimensionally using a total station.