Soils as indicators of the Pleistocene and Holocene landscape evolution in the Alay Range (Kyrgystan)

Soils derived from Quaternary glacial, glaciofluvial and aeolian deposits in the Alay Range (Kyrgystan) were studied to reconstruct the Pleistocene and Holocene landscape evolution. Geomorphologic studies, radiocarbon dating of A horizons in palaeosols, and iron fractionation were undertaken. During the Last Glacial Maximum (LGM) the Abramov glacier in the Alay Range advanced down the Koksu valley to an altitude of 2500 m asl, about 50 km from the modern snout (ELA lowering about 600 m). In addition, several frontal moraine complexes could be identified at the valley bottom of the Koksu river between 3100 m asl and the modern glacier snout at 3650 m asl. The complexes call be assigned to the following glacier advances: Late Glacial (ELA lowering 200-300 m), early Holocene to end of Late Glacial (Younger Dryas?, ELA lowering about 110 m), Neoglacial (ELA lowering about 50 m), and Little Ice Age (ELA lowering about 50 m). Similar glacier advances could be reconstructed according to the soil development on the lateral moraines near the Abramov glacier at 3600-4000 in asl. Determination of pedogenic iron oxides corroborated the morphologic and radiocarbon results. (C) 2000 Elsevier Science Ltd and INQUA. All rights reserved.