Equilibrium-line altitudes and rock glaciers during the Younger Dryas cooling event, Ferwall group, western Tyrol, Austria

Cambridge

International Glaziological Society

1999

S. 141-145

Bandaufführung

89341

Annals of Glaciology, S. 141-145

Three cirques in the Ferwall group, western Tyrol, Austria, which are characterized by distinct Late-glacial moraines and rock glaciers, are discussed. The morphology of the moraines and the depression of the equlilibrium-line altitude suggest they were deposited during the Egesen Stadial (Younger Dryas), which can be subdivided into three substagers. Rock-glacier formationwas initialzed during or after the Egesen II substage. They became inactive at the Pleistocene-Holocene transition. ELA values are 290-320 m lower than the Litte Ice Age ELA during the Egesen I substage, 190 - 230 m lower during the Egesen II substage and 120 - 160 m lower during the Egesen III substage. The lowering of the rock-glacier belt (discontinuous permafrost) during and after the Egesen II substage is about 400 m, indicating a mean annual air-temperature depression in the order of 3 K. During the Egesen I (early Younger Dryas), the climate seems to have been rather cold and wet with precipitation similar to present-day values. During later phases (Egesen II and III), the climate remained cold and become increasingly drier. The rise of the ELA during the Egesen I-III substrages seems to have been mainly caused by a decrease in precipitation.