Bogbean Under Drumlin Ice
At Derryvree, roadworks exposed organic freshwater silts and fine sands enclosed between two bodies of till: unsorted debris deposited directly or indirectly by glacier ice. The sequence provides a powerful relative history. Ice had first occupied the locality and left a lower till. Later, water, vegetation and small animals accumulated organic sediment in ground that was not then under glacier ice. A renewed advance eventually buried that freshwater deposit beneath an upper till.