Dendrochronological study of oak trees found in bogs in Northern Ireland show significant concentrations of extremely narrow rings for periods of less than 20 years, and these dates correspond to dates of major volcanic eruptions. One of these narrow-ring periods begins in 1628 BC (absolute dating) and was probably caused by Santorini (the Aegean island whose date of eruption has been much discussed). Trees growing on bogs are particularly vulnerable to adverse weather conditions, and it is suggested that the dust thrown into the atmosphere by Santorini caused severe climatic changes for a brief period. -- AATA