Radiocarbon Dates for Two Crannogs on the Isle of Mull, Strathclyde Region, Scotland

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Crannogs, the artificial island habitations of the Scottish lochs and lakes, are once more a lively field of research. Following our 1993 report on the crannogs of southwest Scotland and their dates, here is news of crannogs on the Isle of Mull, again with striking dates.

The survey of the crannogs of the southern Hebrides began on the Isle of Mull, just off Scotland's west coast near Oban, where a total of seven crannog sites were identified and inspected. Underwater investigation showed that previously recognized sites were more extensive than had been noted (RCAHMS 1980: 120). While surface inspection indicated that some were constructed primarily of stone rubble, others still contained exposed timbers. These were sampled for radiocarbon determinations where this could be achieved with minimal disturbance to the sites.

Barber & Crone (1993: table 1) have tabulated radiocarbon dates for 12 crannogs. Determinations are now available for a few other mainland sites (Henderson 1994); these broadly confirm previously suggested chronological groupings. Timbers from two sites in Loch Frisa, the largest of Mull's freshwater lochs, were sampled and submitted for dating.

The first site, Eilean Ban, is a stone-covered, circular island 24 m in diameter and almost entirely artificial. Defensive dry-stone walling, thought to date to the 17th century (RCAHMS 1980: 241), crowns the island's surface. The timber (alder) which was sampled is solidly set into the stone mound and appears to be part of the island's man-made understructure. It has produced a determination of 2200[+ or -]70 b.p. (Beta-78832), calibrated at 2[Sigma] to 395-45 BC, setting at least one phase of this site firmly in the Iron Age.

The second site at which timber was identified, Ledmore, is an oval shaped mound of stone, measuring 11 x 13 m, and had not previously been identified as an artificial island. Oak projecting into the loch from the side of this site has furnished a determination of 700[+ or -]50 b.p. (Beta-78833), calibrated at 2[Sigma] to AD 1250-1395. The calibrations are those provided by Beta Analytic, and were obtained according to the conventions contained in Radiocarbon 35 (1993).

The Ledmore date is currently the most recent isotopic determination for a crannog from Scotland and only the second, the other being from Lochrutton (Dumfries & Galloway Region; Barber & Crone 1993: table 1), which dates constructional timber from this type of site to the medieval period. It is surprising that so few crannogs have been dated to this period, as numerous literary sources indicate that crannogs were constructed and in use until the 17th century AD. Thus, the crannogs of Mull were noted as defensive strongholds as recently as 1608, when the Register of the Privy Council of Scotland demanded their surrender to the Crown in an official notice (Morrison 1985: 123). …