Hekla-4 ash, the pine decline in Northern Ireland and the effective use of tephra isochrones: a comment on Hall, Pilcher and McCormac

In response to a paper by Blackford et al. (1992) which showed a coincidence between the deposition of Hekla-4 tephra and a decline of Pinus pollen in two northern Scottish sites, Hall et al. (1994) investigated the tephra/pine pollen relationship at two sites in Northern Ireland. We argue that their sites are inappropriate for such comparison because pine was effectively absent from Co. Antrim long before the deposition of Hekla-4. The opportunity is taken to make some additional points concerning the Irish data and the wider use of tephra isochrones.