Derryvree’s Periglacial Census
The most informative Irish evidence close to this notional date comes from Derryvree, near Maguiresbridge in County Fermanagh. Road works in 1969 cut through a drumlin and exposed an exceptional sequence: a bed of freshwater silts, sands and organic material enclosed between two thick layers of till, the unsorted debris deposited by glacier ice. The order of those deposits is crucial. An earlier glacier had affected the locality; an intervening period then allowed water, plants and small animals to leave a record; later ice advanced and buried it beneath another till.