Arctic ice caps. During the last glacial maximum
(LGM, 20 000–14 000 years before present, yrBP),
the average temperatures were 10–20◦ C lower than
present, permafrost extended to southern France and
Germany, and huge ice caps covered the Pyrenees and
the Alps. Deglaciation in Europe began ca. 14 000
yrBP, but climatic amelioration was interrupted by a
steep reversal, the Younger Dryas, ca. 10 500 yrBP,
a cold and dry stage that determined a southward
spread of tundra and the retreat of temperate forests.