Cardiff Studies in Archaeology - Specialist Report Number 18

RADIOCARBON DATES

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In the course of last years post excavation programme eight radiocarbon dates were obtained from the Research Laboratory for Archaeology and the History of Art, Oxford. Five of these dates were obtained from the Late Iron Age activity on mound 1 and three from the Norse hall on mound 2.

Sample noMoundContextMaterialSpeciesElementdelta 13 CDateStandard deviation
OxA-9638
2
558Bonecattlerib-20.91052
34
OxA-9639
2
557Bonecattlerib-21.11317
39
OxA-9640
1
482Bonecattlemetapodial-20.21699
34
OxA-9641
1
456Bonecattlecalcaneum-20.41790
40
OxA-9642
2
182Bonesheep/goatvertebra (a)-20.41011
39
OxA-9643
1
495Bonecattle1st phalanx (a)-20.71686
33
OxA-9665
1
495Bonered deertarsal (a)-21.61705
50
OxA-9677
1
453Bonered deercalcaneum-21.41580
60

The five samples from mound 1 came from two areas: the hearth, which belongs to the second period of occupation of the Late Iron Age house, and from the midden layers present in the trench on the western side of the mound. The first two dates effectively bracket the second period of occupation in the house. 9640 was from one of the metapodials that surround the hearth and suggests the house was reoccupied between AD260 and 410 (68.2% probability). 9677 was from a bone placed in the final layer of the hearth and suggests the last activity inside the house occurred between AD410 and 560. The three dates (9641, 9643, 9665) from the midden layers indicate these were deposited between the end of the second century AD and the end of the fourth century AD and confirm the view that they are contemporary with the occupation of the house.

The three dates from mound 2 were specifically designed to confirm the dating of the 'secondary occupation' of the substantial house. Two (OxA-9638, 9639) came from material resulting from the occupation of the structure and one (OxA-9642) comes from the final layer, which marks the end of this occupation. There is very close agreement between 9638 and 9642 and after calibration these dates suggest occupation around 1000 Cal AD. However, sample 9639 is not very helpful being some 300 years earlier. This was an almost complete cattle rib, which was selected because it was fresh and did not appear to be redeposited. The only explanation for its presence on this house floor is that it was deliberately selected from earlier midden deposits and brought into the house for a particular purpose. It does provide some confirmation that the Norse remains on mound 2 are built into a Late Iron Age settlement that bridges the period between the occupation in mound 1 and the Viking settlement of the islands.

These eight dates are the first of many dates planned for the site and with one exception (9639) appear to provide an accurate chronology for the contexts dated. They indicate an assemblage of double cordoned everted rim vessels (Dun Cueir Ware) dates to the third and fourth centuries AD. This fits in well with the earlier radiocarbon dates from Sollas (Campbell 1991) and Cnip (Armit forth) which both have assemblages of elaborately decorated everted rim ceramics which were assumed to precede the development of the forms from Bornais (Lane 1990). The final date from the fifth to sixth century date from the hearth is interesting as it precedes the accumulation of a series of occupation deposits with an assemblage which includes double cordoned everted rim wares and straight sided vessels.

The two acceptable dates from the Norse house confirm the house dates to the eleventh century and if anything suggests it may belong to the first half of the century rather than the second half. This would support the accepted date of the Ringerike style rather than the proposed date for the imported pottery.

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