Location, Topography and Discovery
Thirlings is on the sand and gravel terrace surface of the Milfield Basin in the North of Northumberland in England, 15km from the Anglo-Scottish border and 5km from the small market town of Wooler (NGR: NT965322). The land is currently under arable cultivation and no archaeological features are visible on the ground surface. The site was discovered through cropmarks, photographed by Dr. J.K. St. Joseph of Cambridge University and Professor N. McCord of Newcastle University. It was excavated between 1973 and 1981 by Roger Miket and Colm O'Brien.

The site had been a focus of activity on two occasions during the Neolithic era, from which episodes pits containing pottery fragments were identified. In the early medieval period, there was a group of rectangular buildings of timber construction; 12 were identified in the excavations. No boundary fence was identified for the group as a whole, but two buildings (designated "A" and "P" in the excavation record) which were positioned towards the centre of the grouping stood within their own fenced compounds; no other building was similarly positioned within a compound. This suggests that these two buildings had some primacy of function or status within the set. Building A is the model for the Bede's World experiment.

Of the 12 buildings, three were smaller than than the others with floor areas in the range 21 to 27 square metres; the others nine ranged in floor area from 45 square metres to 96 square metres. Building A is 74 square metres. These are smaller than the large halls of the Yeavering palace, but they are towards the larger end of the range of buildings so far discovered on other sites of this period in England.

There was little direct evidence, apart from the building structures themselves, for the activities and lifestyle of their inhabitants; probably they lived as a farming group at some time during the 5th - 6th centuries AD, on the evidence of radiocarbon dates.

Nature of the archaeological evidence
Intact archaeological features survive below the depth of the ploughsoil which is turned over every year in farming. On the light sandy soils of the site, the ploughsoil is some 25 - 30cm (10 - 12 inches) deep. Consequently, the only survivals are the foundations of buildings and the in-fillings of other cuttings made into the ground. These may be boundary and drainage ditches or pits dug into the ground for storage or rubbish disposal.

Excavation begins with the ploughsoil which may, at a preliminary stage, be examined in some test pits. The normal technique is then to remove the ploughsoil with a machine. The back bucket of a JCB or similar excavator is frequently used. This exposes the underlying surface of the sub-soil. This is scraped clean carefully, usually with hand trowels.

The excavation depends on observation and analysis of fine variations in the colours and textures of the sub-soil surface. These variations allow the excavator to distinguish between the undisturbed ground which was laid down by geological processes and the patches of ground which have been disturbed. These are the patches which produce the cropmarks. Some of these disturbances have been caused by frost action during the glacial era. Others are of human origin, such as the building foundations in which a trench has been cut into the ground, timbers set and the earth replaced. Excavation is then a matter of dissecting these features, observing and recording their constituent materials and any objects which they may contain.

Interpretation
Interpretation of the structure and the appearance of the buildings depends on first of all on the direct archaeological evidence, and then on the inferences which can be drawn from that evidence. The evidence is limited to the foundation levels of the buildings, with no flooring and no superstructure surviving. Consequently different interpretations are possible of the nature of panel in-fills in the walls and the roof structures, and features such as window openings are a matter of speculation. However, the remains at foundation level do provide reliable evidence of the principal upright timbers in the walls, in the interior of the buildings and outside.

No timber survived in the ground: it is too acidic to allow preservation of organic materials over that length of time. Evidence of the positions and the sizes of timbers was of three types. First, dark staining at the base of the foundation trenches and post holes which is caused by organic decay of the ends of the timbers. This was sometimes accompanied by slight depressions where the weight of the timber had pressed down on to the gravel base. Second, places within the foundation trenches which had been excavated deeper to hold larger posts. Third, material which collapsed into voids left in the foundation trenches after timbers had been removed (the building under consideration here had been demolished after its period of use). Not all uprights were detected in all buildings, but enough evidence survived in these forms to demonstrate that the walls were formed as post-and-panel structures, to show the positions of doors, to show the size of timbers in use, and to show when larger timbers had been used and set more deeply.

Structural Considerations
The buildings at Thirlings conform in their basic constructional technique and architectural details to a type which was widespread in England in the Early Medieval period, and has been identified in places as far apart as Northumberland and Hampshire. (See Simon James, Anne Marshall, Martin Millett "An Early Medieval Building Tradition." Archaelogical Journal Vol 141 (1984), 182-215.) They are built to variations of post-and-panel design. This is a structural system which uses load-bearing uprights of timber at intervals along the wall lines and in-filling panels between the timbers. The uprights are held firm by being set into the ground, either in foundation trenches or in individually dug post holes. This technique of earth-fast support is an older tradition than the timber framing of medieval building, in which the uprights are morticed into sill beams, and in which structural rigidity is ensured by the resolution of forces across a box-like structure.

Six of the set of buildings at Thirlings have their main wall timbers set in construction trenches, while others use individually dug post holes. It is difficult to assess the significance of this variation in foundation design which has no bearing on the structural integrity and would not have been apparent when the buildings were in use. Post settings within the buildings appear to mark partitions at the ends, but these timbers may also have acted as an internal structural system supporting the roof members. There is also evidence in some of the buildings for external supports on the long sides. It is not clear how these timbers were positioned, but the evidence from some comparable buildings at other sites suggests that they were angled in towards the wall lines. This means that they acted as bracing or buttressing and not to support lean-to sheds along the walls.

There is good evidence for a degree of standardisation in the specifications for timbers and for precision in the workmanship. Some of the principal uprights are squared off, others are circular, and both diameters and side lengths of about 300mm (1 foot) are frequently used. Three buildings have a distinctive wall-type which uses timbers in pairs to clasp horizontal planking. The pairs are formed from squared planks with dimensions 130 by 260mm (about 5 inches by 10 inches), placed in pairs with an 100mm metre (4 inch) gap in between.

Note:
The text of this page is based on the definitive publication of the Thirlings excavation by Colm O'Brien and Roger Miket: "The Early Medieval Settlement of Thirlings, Northumberland." Durham Archaeological Journal Vol. 7, 1991, 57 - 91. Users who wish to read a more detailed statement of the evidence and analysis should refer to this paper.