Derryvree’s Alternate Water-Milfoil
Derryvree was exposed in roadworks in 1969. The section contained silts and fine sands with organic material between two thick tills: sediments laid down directly by glacier ice. That order is crucial evidence. It establishes that glaciation occurred, that a freshwater environment subsequently existed at the site, and that ice later returned to cover and preserve the deposit. It does not mean that all Ireland was ice-free at once, nor that the Fermanagh basin was a stable refuge for millennia.