Sunken featured building (SFB for short) is a term used in early medieval archaeology alongside the German term Grubenhaus (plural Grubebhauser) to describe a particular type of small to medium sized timber building, constructed in northern Europe from the 5th to the 12th century AD. Such structures are part of a tradition of buildings with sunken floors, or partially subterranean elements, that span thousands of years of use. In this wider sense the term pit-house (Pit-house) is often used.
In Trench 1 we have been referring to traces of a structure in the SE corner of the trench as an SFB. In this case we have been using the term as short hand, as although the structure is slightly sunken into the ground, it does not have many of the characteristics we would expect of an early medieval SFB. They tend to be relatively easily identified as cut features, although often eroded. Ours, though broadly rectangular, is quite difficult to define and seems to have been formed from erosion of a floor rather than having been deliberately dug. Also classic SFB’s tend to have post-holes located centrally to the short walls, indicating a gabled roof. Our feature, so far, appears to have a central post, supported by a re-used quern stone.
Other factors also place our enigmatic feature outside of the general tradition. It is not associated with an industrial or workshop area. That lies in the area of Trench 3. Most of all, SFB’s are found on very different subsoils, such as sands and gravels, where excavation below ground level is a relatively easy option to increase the internal volume of a building. Our strange feature lies on boulder clay, which is pretty difficult stuff to dig. Ask any of our excavators!
In the next few days we should have excavated the last of the material within the hollow. Already we are seeing what appear to be features beneath it. The interesting question will be, are these features associated with the overlying structure, or a new phase of activity beginning to show up.