INVESTIGATION OF THE ENVIRONMENTAL-IMPACT OF REMOTE VOLCANIC ACTIVITYON NORTH MAYO, IRELAND, DURING THE MIDHOLOCENE

Seven layers of microscopic tephra have been detected in ombrotrophic peat from western ireland. A radiocarbon chronology suggests that two of the tephra layers were deposited around 4000 BP. Pollen, fungal spo res and testate amoebae have been analyzed from the pear immediately a bove and below the tephra layers. These analyses provide information o f changes in the landscape surrounding the bog and as well as conditio ns on the bog surface. Analysis of rates of change in these data has b een employed to investigate the relative magnitude of environmental ch anges at the time of tephra deposition. Tephra deposition occurred at least 100 years after a major decline in Pinus pollen and coincides wi th fairly stable conditions in the terrestrial environment. More signi ficant changes on the bog surface, indicative of wetter conditions, ar e associated with the timing of tephra deposition.