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

Recent research has demonstrated the presence of annual luminescent gr owth banding in a stalagmite from Sutherland, N.W. Scotland (Baker, Sm art, Edwards and Richards, 1993). The banding record of this sample co ntains a short duration increase in annual band width, indicating a do ubling of growth rate for a period of four years. Predicted growth rat es derived from calcite precipitation kinetics are compared with obser ved growth-rate variability to demonstrate that such a doubling of gro wth rate would not be expected within the probable range of normal cli mate variation. The growth rate peak is dated to 1135 +/- 130 BC by th ermal ionization mass spectrometric U-238-U-234-Th-230 dating, not inc onsistent 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 explosiv e eruptions.