Derryvree’s Arctic Lake
In global archaeological terminology, Ireland lay in the later part of Marine Isotope Stage 3 (MIS 3), an unstable interval of the Last Glacial Period. It preceded the coldest and most extensive phase of the Last Glacial Maximum, but was not a uniformly mild respite before the ice. North Atlantic climates swung sharply between colder stadials and relatively warmer interstadials. Ice masses, sea level, vegetation and animal routes could alter over periods far shorter than the immense span suggested by a date in BCE.