Sunday, October 26, 2008

THE NORTHERN IRON AGE

Castle Law Hillfort - this photo shows the earth banks and terraces of the hill fort.



Castle Law fort, Abernethy (Perth), showing the slots for timber lacing on the outer face of the inner wall. (R.C.H.M. Scotland)


In most parts of Scotland after the climatic deterioration at the beginning of the first millennium BC, there was a gradual expansion of the population. Bronze Age traditions survived and there was cultural continuity through into the Iron Age. Regionally the country is very diverse, with sparse settlement along the edges of the Atlantic coast and in the north-east, and greater density between the Tyne and the Forth, and along the Solway and Clyde estuaries.


The most intensive research has taken place in the Tyne and Forth area and this might slightly distort the overall view. Tiny hillforts, often less than a hectare in extent, are thick on the ground there. Hownham Rings (Roxburgh), developing from palisaded enclosure to defended hillfort, has already been quoted, and this sequential pattern seems to have been common, though many palisaded homesteads existed side by side with hillforts. The excavation of Broxmouth, on a low hill near Dunbar (East Lothian) revealed a very complex hillfort. An unenclosed homestead containing a single round house was succeeded by a fort with a single rampart and ditch. This defence was later doubled, and then reduced to a univallate form with a variety of entrances throughout. Five wooden round houses each about 11 m. (12 yd) in diameter, were detected in the fort, as well as circular stone-built examples which were later than the defences. The latter had timber posts to support the roof and beaten earth floors. Later the floors were paved and the roof posts must have stood on stone supports. A deposit of ox skulls beneath a house wall may have been a dedication burial.


Most hillforts in central and eastern Scotland were timber-laced. This means that horizontal timbers were laid within the core of both stone walls and earthen ramparts, rather than being set vertically as in southern Britain. Sometimes when the fort accidentally caught fire (or was deliberately fired) the timbers burnt at temperatures over 900°C, causing the stones to fuse together producing vitrification. This is seen clearly at Carradale (Argyll) and Dunagoil (Bute). There has been much debate as to whether vitrified forts were the result of a deliberate attempt to strengthen the defences, but the general consensus seems to be against the suggestion. Although some very early radiocarbon dates have been obtained for timberlaced forts, a beginning perhaps in the eighth century BC seems most acceptable. Finavon (Angus) is the best known of the timber-laced forts which suffered extensive vitrification. Although only enclosing 0.4 ha. it is defended by a massive stone wall some 6 m. thick, surviving to a height of 4.9 m. externally. Excavation by Gordon Childe in 1933–4 showed that only the top of the wall had vitrified, perhaps because the upper section had contained more timber to strengthen it. The excavator found traces of timber houses against the fort wall, and hearths, a possible oven, domestic refuse and crucibles for metalworking. Childe also uncovered a rock-cut cistern or well to a depth of 6.3 m. Such cisterns occur in other north-eastern forts, such as Castle Law (Abernethy, Midlothian). This latter site, also excavated by Childe, passed through at least three phases consisting of palisade, single timber-laced rampart and multivallate fort. In the fort ditch an underground storage place or souterrain had been constructed, similar to the Cornish fogous. About 200 examples of souterrains are known from northern Scotland, though most are dated between the last century BC and the third AD. Those in Orkney and Shetland tend to be entirely underground, but in eastern Scotland they are only partially subterranean. As in Cornwall their function is uncertain though storage seems to be most probable.


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