Mapping the inside of Dorset’s hillfort enclosures

Overlooking Hambledon Hill, one of Dorset’s most famous hillforts. Recent geophysical survey has shed new light on the archaeology of its interior. (Image: Jo and Sue Crane)

Across Dorset, impressive earthworks mark the location of Iron Age hillforts. Until recently, though, little archaeological attention had been paid to what lay within these mighty ramparts. Now, thanks to modern geophysics, the picture is beginning to come into focus, as Dave Stewart and Miles Russell explain.

Hillforts are among the most dramatic and visually striking archaeological monuments in the British Isles. Appearing from the late Bronze Age and reaching their peak in the middle Iron Age, Dorset is particularly rich in such enclosures, with 35 – including the internationally famous sites of Badbury Rings, Hambledon Hill, Hod Hill, and Maiden Castle – having been recorded to-date. In recent years, detailed geophysical surveys have been undertaken, with some success, at a number of British hillforts, but the Dorset sites have unfortunately been rather neglected. This is something we have been keen to correct.

Since 2009, Bournemouth University has been investigating Iron Age and Romano-British settlement patterns across south-western Britain, and initial excavation at a number of sites around Winterborne Kingston, near Bere Regis (see CA 281 and 313), was complemented by an intensive programme of geophysical survey. Creating detailed records of the subsurface features of hillforts was, we felt, particularly important in order to help improve understanding of the form, phasing, structure, and possible function of these impressive prehistoric enclosures.

What, then, is a hillfort? The term is, as many have noted, one of convenience: a useful, if not always entirely topographically accurate, archaeological descriptor, not all of such monuments being found on the highest points in the landscape. Neither, it must be acknowledged, is an association with fortification always helpful, for many enclosures may originally have been designed for purposes other than simply defence and military engagement.

Iron Age hillforts are scattered across Dorset. Many have yet to see archaeological exploration.

Most recognisable forms of hillfort appear from around 600 BC with the univallate (single rampart) enclosures of the early Iron Age. Averaging 5ha in extent, the shape of these earthwork circuits generally conforms to the contours of specific points in the landscape, and their entrances are usually quite simple, with either one or two opposing breaks in the banks. By the middle Iron Age, many of these primary enclosures had been abandoned, although a few were extended and developed into more complex multivallate sites like Maiden Castle. Unfortunately, until the late 1970s, the archaeological exploration of hillfort interiors was relatively rare, with excavators tending to focus instead on sequences of rampart construction. Since the 1980s, though, detailed investigation, geophysical survey, and aerial photography have transformed the field, suggesting that, while certain enclosures contained areas of settlement and storage, others possessed very little evidence of intensive activity at all.

The appearance of these more defined and complex forms of hillfort enclosure may reflect broader developmental changes in early and middle Iron Age society, with communities feeling the need to increase control both of the land and the storage of resources. These sites could have had diverse functions: some hillforts may have acted as welldefended zones of semi-permanent elite settlement, others as places of storage and redistribution, while still more may have performed a more overtly religious and ceremonial function. By the 2nd century BC, though, only a limited number of British hillforts remained in use. Those that survived to this point developed rampart sequences and increasingly elaborate forms of entranceway – but in most areas of southern Britain, throughout the very late 2nd and early 1st century BC, hillforts seem to have been in a marked decline, with only a few apparently continuing in use at this stage.

Seeing Beneath the Soil

Having carried out more than one survey in sub-zero temperatures and gale-force winds, it seems amazing that anyone would voluntarily live on these exposed hilltop sites, yet people were clearly doing just this, and in some numbers. Geophysics has produced compelling evidence of roundhouses invisible to the naked eye – so many of them that it is probable that the actual level of habitation on all such sites has been severely understated. Across the survey, we could see a wide range of discrete internal forms, ranging from limited scatters of pits and features to pits clustered into distinct zones, pits associated with roundhouses, and intensive distribution of roundhouses and other built forms divided and arranged by roads and trackways.

Maiden Castle was excavated by the Wheelers in 1934-1937. Mortimer Wheeler interpreted their findings as evidence of a bloody Roman attack on the hillfort. (Image: Jo and Sue Crane)

Three distinct forms of prehistoric roundhouses emerged during our project. The first, defined as a ‘Pimpernestyle’ roundhouse (named after a Dorset site dug in the early 1960s), has a ring ditch measuring between 10m and 15m in diameter, with an entrance generally facing south-east. We have seen examples of such structures at Abbotsbury, Hod Hill, Pilsdon, Maiden Castle, and across the flatter areas of Hambledon Hill. Other house platforms at Hod Hill have no apparent ring ditch: they appear similar to dwellings recorded from the settlement outside Poundbury hillfort, where ring-slot walls measure about 7m diameter.

These ditches were probably intended to help keep the hut floor dry and to prevent the daub wall from getting excessively damp and crumbling, but in steeper terrain they do not seem to have been necessary. In environments like these, house platforms seem to have generally been terraced into the side of the slope. At Abbotsbury hillfort, for example, these surfaces appear to have had a ditch on the uphill side only, with the natural incline presumably carrying any water away downhill. Similar terraces are also seen in some numbers in the south-west quadrant of Hod Hill, a part of the hillfort that has undergone severe plough damage, though no ring ditches can be seen there. Their presence at sites like Abbotsbury could signify that such features did originally exist here too, but have since been erased through modern farming. On Hambledon Hill, the slope is steeper still, and most of the site’s dwellings are terraced into the hillside, but no ditches are evident – yet ploughing is unlikely to have been instrumental in their removal, as the platforms appear generally well preserved. Perhaps here the angle of the terrain by itself was sufficient to prevent the dwellings from becoming waterlogged.

Ringing the changes

The full magnetometry plot for Maiden Castle, revealing new clues to the features that lie within its ramparts.

Other clues to how these settlements operated have also come to light during our survey: the layout of the recorded house structures shows a significant degree of interior planning, and where gaps between groups of structures and pits can be identified, these may be interpreted as some form of roadway or thoroughfare. Some of these incorporated earlier features: at Maiden Castle, a Neolithic bank barrow splits the hillfort lengthwise, apparently forming the spine for a herringbone pattern of cleared Iron Age pathways. The long barrow within Hambledon hillfort may similarly have formed part of a track through the narrow central part of the enclosure, while a broad path takes a direct route between the two southern gates. At Spettisbury, two possible tracks branch from the entrance, terminating against the southern rampart, perhaps betraying remodelling and an earlier second entrance that had since become defunct. Meanwhile, a single trackway through Buzbury hillfort indicates that a gap in the southern rampart, lying east of the current entrance, was this site’s original gateway.

Within Hod Hill, the most striking aspect of the geophysical plot is the number of circular anomalies representing structures – over 200 in total – which are so densely packed that their footprints often overlap, suggesting a long period of occupation. Each of these appears to contain one or more strong pit-like anomaly – comparison of magnetometry and resistivity plots here indicate a mixture of hearths and pits, some probably combining both. A line of similar pit-like features without ring ditches appear near the eastern rampart, and a scattering of the same have been detected in the south-west.

To the north-east of the enclosure, we can also deduce further evidence of planning: the tree-like branches of a road system, extending from the Steepleton Gate, is hinted at from the lack of cut features rather than as a positive feature in its own right. Through such negative features, we can see other Iron Age amenities in great detail: some sections of both main and minor trackways are bounded by ditches, apparently created by the gullies surrounding structures being linked to form a continuous drainage channel. A higher-resolution plot of one such section, near a junction, showed it to be also bordered by rows of fourpost structures, generally about 2.5m square with four or, in two instances, five post-holes, probably representing storage buildings such as granaries.

At Hod Hill, magnetometry revealed over 200 circular anomalies representing structures, as well as an extensive road system. This detail of the survey plot shows trackways extending from the Steepleton Gate at the north-east (top right) and some of the densely packed roundhouses, hearths, pits, and fence lines.

Various other branches of the trackways terminate at areas of magnetic scatter below the ramparts or appear to divide the internal area into blocks of features. Within each of these blocks, a closer look at the magnetometry reveals at least one structure surrounded by its own enclosure, possibly relating to areas of administration and control. Finally, in the south-east corner there are two areas abutting the quarry pits that appear to be screened with palisades. We can see traces of possible smallscale internal enclosures at Poundbury and Banbury hillforts too, although here the survey responses are generally weak. Maiden Castle’s two enclosures are much more clearly apparent: the northernmost seems to have started life as a single oval measuring 30m long, before being later doubled in length, while that established to the south is some 60m across and could have formed an individual enclosed farmstead in its own right.

How should we interpret these findings? The potential number of dwellings inside Dorset’s developed hillforts seems excessive if the enclosures originally acted only as the type of temporary refuge with which they have been traditionally associated. On the contrary, overlapping buildings indicate occupation over a long period, which also makes it unlikely that the structures simply housed the huge workforce required to raise the ramparts in the first place. The traces of industry and the artefacts found in the various excavations at such sites suggest that, by the middle Iron Age, developed hillforts had become permanently occupied centres, possibly akin to market-towns, with resident storage facilities and craftspeople.

This article was featured in CA 336.

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