Late Pleistocene glaciers in Greece: A new 36Cl chronology

Glaciers formed in the highest mountains of Greece during the Late Pleistocene, but the timing of glacier maxima is poorly understood. This paper presents 27 36Cl terrestrial cosmogenic nuclide exposure ages from glacial boulders on Mount Tymphi (2497 m a.s.l., 40oN) in Epirus, northwest Greece. These ages address both a significant geographical gap in Mediterranean glacial chronologies and a temporal gap in the glacial history of this region by targeting the previously undated Late Pleistocene record. Late Pleistocene glaciers were restricted to the cirques and upper valleys of Mount Tymphi. Terminal and lateral moraines between 1700 m and 2050 m a.s.l. mark the extent of Late Pleistocene glaciers on the southern side of Mount Tymphi. Moraines marking the maximum extent of Late Pleistocene glaciation date to 29.0 ± 3.0 ka and 25.7 ± 2.6 ka, taking the oldest ages as most representative of moraine emplacement. Glaciers had retreated to the high cirques by 24.5 ± 2.4 ka during Heinrich Stadial 2. Rock glaciers formed under cold and drier conditions during this period of glacier retreat. This 36Cl dataset complements published U-series ages from secondary calcites in glacial sediments below 1700 m elevation, which demonstrate more extensive Middle Pleistocene glaciations in MIS 6 and MIS 12. A Late Pleistocene glacier maxima on Mount Tymphi at 25.7–29 ka is in good agreement with well-preserved outwash sediments dating to 24–28 ka in the Voidomatis River record downstream and is consistent with the Ioaninna basin pollen record indicating cool and wet conditions, most favourable for glacier growth, at 25–30 ka. •Glaciers formed in the highest mountains of Greece during the Late Pleistocene.•Late Pleistocene glaciers were restricted to the cirques and upper valleys of Mount Tymphi.•These glaciers reached their last maximum extents at 25.7–29 ka during cool and wet conditions.•Glaciers had retreated to the high cirques by 24.5 ± 2.4 ka under cold and drier conditions.•36Cl TCN dating of glacial activity agrees with the independently-dated record of river behaviour.