Why Ring a Hilltop With Ditches? The Answer Is Not Only Defence

The characteristic form is one or more circuits of bank and ditch following the contour of a hill, enclosing an area that ranges from under a hectare to well over fifty. The banks were revetted with timber or stone and topped with a palisade, and the ditches were cut into rock where necessary, which represents an enormous quantity of labour with hand tools. Entrances are the most elaborate part, frequently formed as long inturned passages with gates partway along, which forces anybody approaching into a confined corridor. Many were rebuilt and enlarged repeatedly over centuries.

Excavation reveals more variety than the name suggests:

• •Roundhouses in numbers, at some sites hundreds of them
• •Four-post structures generally read as raised granaries
• •Storage pits cut into the rock, in very large quantities
• •Evidence of metalworking, weaving and other craft
• •At other sites, almost nothing at all inside the circuit
• •Deliberate deposits of objects, animals and human remains in pits

Interpretation has swung considerably and the current position is uncomfortable with the traditional one. The defensive reading fits the elaborate gateways, the evidence of burning at several sites and the discovery of sling stones stockpiled in quantity. Against it, many sites enclose far more ground than could be defended by any plausible population, some have entrances that are elaborate but tactically poor, some have ditches on the uphill side where they achieve nothing, and many show little sign of permanent occupation. Alternative readings treat them as displays of communal status, as seasonal gathering places, as stock enclosures, or as ceremonial sites, and the honest position is that different sites probably served different purposes.

Recording these sites has changed completely in a generation, and the new methods keep finding ones nobody knew about. Airborne laser scanning maps ground surfaces through tree cover, which has revealed circuits inside woodland that were invisible on the ground and from the air, and surveys in Britain, Ireland and central Europe have added substantially to the recorded total. Geophysical survey detects buried ditches, pits and hearths across a whole interior in days without excavation, which reveals how densely occupied a site was without destroying anything. Aerial photography in drought years shows crop marks over buried features. Combined, these have shifted the discipline from excavating a few sites to comparing hundreds.

Occupation of these sites declined across much of Europe in the last centuries before the common era, and the reasons vary by region. In southern Britain many were abandoned well before the Roman conquest, with settlement shifting to lower ground and to large sprawling enclosures that look more like trading centres than strongholds. Where sites were still occupied, Roman military action ended it, and several show destruction deposits. A number were reoccupied and refortified centuries later during the unsettled period after Roman withdrawal, which complicates dating any given bank without excavation. Some were reused again in the medieval period as castle sites, since the earthworks were already there.

Circuits of bank and ditch around hilltops represent enormous labour and are traditionally read as defences, which fits the elaborate inturned gateways, the burning and the stockpiled sling stones. Against that, many enclose more ground than could be held, some have ditches where they achieve nothing, and many show little permanent occupation. Different sites probably served different purposes, and the name assumes one answer.