THE HEKLA-3 VOLCANIC-ERUPTION RECORDED IN A SCOTTISH SPELEOTHEM

Recent research has demonstrated the presence of annual luminescent growth banding in a stalagmite from Sutherland, N.W. Scotland (Baker, Smart, Edwards and Richards, 1993). The banding record of this sample contains a short duration increase in annual band width, indicating a doubling of growth rate for a period of four years. Predicted growth rates derived from calcite precipitation kinetics are compared with observed growth-rate variability to demonstrate that such a doubling of growth rate would not be expected within the probable range of normal climate variation. The growth rate peak is dated to 1135 +/- 130 BC by thermal ionization mass spectrometric U-238-U-234-Th-230 dating, not inconsistent with the timing of the Hekla 3 volcanic eruption. This event may explain the observed variation in growth rate, and provide a new source of evidence for interpretation of the effects of large explosive eruptions.