Radiocarbon dating tephra layers in Britain and Iceland

Focuses on Icelandic tephra layers at both proximal and distal sites and considers three strategies to obtain age estimates: 1) the conventional dating of individual profiles; 2) high-precision multisample techniques or 'wiggle-matching' using stratigraphic sequences of peat; and 3) a combination of routine analyses from multiple sites. The first approach is illustrated by the dating of a peat profile in Scotland containing tephra from the AD 1510 eruption of Hekla. This produced a ¹⁴C age compatible with AD 1510, independently derived by geochemical correlation with historically dated Icelandic deposits. More precise dates for individual tephras may be produced by 'wiggle-matching', although this approach could be biased by changes in peat-bog stratigraphy close to the position of the tephra fall. As appropriate sites for 'wiggle-match' exercises may be found only for a few Icelandic tephras, also considers the results of a spatial approach to ¹⁴C dating tephra layers. Combined dates on peat underlying the same layer at several sites to estimate the age of the tephra: 3826 ± 12 BP for the Hekla-4 tephra and 2879 ± 34 BP for the Hekla-3 tephra. This approach is effective in terms of cost, the need for widespread applicability to Icelandic tephra stratigraphy and the production of ages of a useful resolution.