Birmingham 3000 years ago
Over 30 "burnt mounds" have been found in Birmingham. These are low mounds, usually 10 to 15m across, composed of heat-shattered stone, charcoal and ash. Some of Birmingham's burnt mounds have been dated to between 1500 and 1000 BC by radiocarbon dating of the charcoal.
Excavation of a burnt mound visible as a layer of burnt stones in a stream bank at Cob Lane in Bournville in 1980 and 1981 showed that it originally lay in a stream meander. Under the burnt mound, there were a burnt hollow, a timber and clay-lined pit next to the former stream bank, and many holes resulting from pointed branches being pressed into the ground. The former stream bed contained remains of beetles. The different beetle species indicate what the environment was like 3000 years ago, and included species usually found where animals are grazing. The silty clay on that the mound had accumulated is likely to be soil which had been loosened by ploughing on the slopes above the site, providing further evidence for prehistoric farming.
The burnt mound mystery: kitchen or sauna
Burnt mounds are usually interpreted as the debris from when ancient people made water boil to cook food by dropping heated stones into it. Although experiments have shown that this could have been the case, we would expect to find animal bones and other debris from food preparation and cooking.
Another interpretation is that they are the debris from steam or sauna-type bathing. In North American Indian sweat lodges, steam is produced for bathing by pouring water over heated stones inside a tent or hut. Reconstructions based on the excavated evidence from the Cob Lane site and the structures used by North American Indians have shown that burnt mounds could well have been saunas.
The reconstruction consists of a hearth on which the stones are heated and a tent on a framework of bent-over branches. The heated stones are placed in a hollow inside the tent and water ladled onto them from a clay-lined pit, to produce steam.
This reconstruction replicates all the features found in the Cob Lane excavation: the shattered stones and charcoal which is the debris from the hearth, the holes resulting from the pointed branches used to make the tent, the burnt hollow which is where the hot stones are placed, and the clay-lined pit next to the former stream line.