Mammoths Before the Advance
Derryvree is exceptionally important because it preserves organic-rich freshwater silts between two layers of glacial till. Such a sequence records a spell when water, plants and animals occupied a lowland basin before later ice overrode and sealed it. The deposit cannot supply a diary of Ireland in 31,641 BCE; its dates and sediments represent an accumulated environmental interval. Yet pollen, seeds, plant fragments and insects can illuminate conditions in the north-west of the island during a period for which archaeological sites are almost wholly absent. They indicate open, cold ground rather than forest: a wet tundra or muskeg landscape with shallow pools, abundant mosses and plant matter, surrounded by sparse vegetation able to withstand long, severe winters.