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Publication Account

Date 2002

Event ID 575358

Category Descriptive Accounts

Type Publication Account

Permalink http://canmore.org.uk/event/575358

HU31 4 OLD SCATNESS ('Virkie', 'Sumburgh Airport', 'Scatness')

HU390107

Multi-period settlement with broch, wheelhouses and later dwellings in Dunrossness. An arc of the broch wall was exposed in one side of a green mound during the building of the perimeter road at the airport at Sumburgh Head in 1976 [1]. In 1995 excavations were started following a geophysical and topographical survey [2]. By 1996 the circular building had been further revealed, together with ash midden material which had evidently accumulated against it. The broch seems to be standing several metres high with a battered outer wall face; the present dimensions (diameter of c. 18m and a wall thickness of 3m) are therefore likely to be too low.

This site is likely to be at least as important as Jarlshof, and the multi-disciplinary research team involved will doubtless extract a much greater variety of information that was possible at the former site. Excavations are still continuing in 2002.

The excavation director, Dr Steve Dockrull, has recently written the following [4].

"The unique nature of the site -- in terms of preservation, recovery and time period -- provides an unparalleled opportunity to develop an absolute chronological sequence. The stratigraphy, the sequence of layers, provides a relative framework. To this, we have now added over 70 absolute dates using three methods: radiocarbon, archaeomagnetism, and optically stimulated luminescence (OSL).

The backbone of the sequence is provided by the accelerator mass spectrometer radiocarbon dating of carbonised barley grains from secure contexts recovered by flotation: this gives the date of harvesting for each grain. Archaeomagnetic methods are used by Dr Cathy Batt to give the date when hearths and ovens were last fired The OSL dating, by Dr Ed Rhodes of Oxford University, tells us when mineral grains were last exposed to light - a method that has been applied to various deposits, including middens, hearths, wind-blown sands, and buried soils.

Work on dates continues, but the sequence that is emerging provides clear evidence to challenge commonly accepted dates for structures like these at Old Scatness. Especially important are the mid-Iron Age dates for the group of structures to the south-west of the broch, one of which (structure 14) is clearly paralleled by an aisled wheelhouse at Jarlshof. Archaeomagnetic and radiocarbon dates indicate that this group (of buildings) is broadly contemporary and belongs to the period 400 BC - AD 1. The group includes a piered wheelhouse 10m internal diameter (structure 12) which had been filled with ashy waste. Radiocarbon dating of plant material and a sequence of OSL dates on quartz inclusions within the deposits indicate that the dump dates to c. 100 BC to AD 100 Excavation of these structures has not yet reached primary floor surfaces, but, given that they were definitely built after the broch, and given the date of material dumped inside them once they went out of use, the Old Scatness broch must considerably predate the generally accepted range of 100 BC to AD 1 - though by how much we will not know until we excavate down to the primary levels in the broch itself.

The length of the Iron Age chronology is indicated by dates from late Iron Age structures in the south-eastern group of buildings. These were inserted into earlier mid-Iron Age buildings which have yet to be dated. For example, a triangular piered wheelhouse (structure 6), 5m in diameter, has been excavated through at least four floor surfaces, each associated with a central hearth, to its primary floor surface.

These deposits have given a sequence of radiocarbon and archaeomagnetic dates which allow detailed interpretation of the use and re-use of the building. It was in use up to AD 800, and was therefore contemporary with the Pictish buildings (including the cellular building, structure 7, inserted into the broch), which are dated c. AD 600-900. A large Pictish painted pebble was found within the primary levels of a second late Iron Age wheelhouse (structure 11). This building, it seems, was deliberately infilled during the early Norse period to create a level floor. Excavation of this floor revealed a long hearth characteristic of the Norse, and a group of soapstone and schist loom weights lying just as they had fallen from the loom.

A number of later buildings and midden deposits take this occupation sequence through to the mid-twentieth century. "

Sources: 1. OS card HU 31 SE 21: 2. Discovery and Excavation, Scotland, 1995, 104-05; 1996, 94-5: 3. Nicholson and Dockrill, eds., 1998: [4] Current Archaeol. no. 177 (Jan. 2002), 387-88.

E W MacKie 2002

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