New age constraints of the LGM onset in the Bohemian Forest – Central Europe

Abstract

During the Last Glacial Maximum (LGM), valley glaciers in the Bavarian/Bohemian Forest mountains (Central Europe) reached their maximum extent, forming prominent terminal moraines. In this study, we provide the timing for the terminal moraine complex in the south-facing Großer Schwarzbach Valley using in situ produced cosmogenic 10Be dating. The moraine complex was deposited during the onset of the LGM, as indicated by the weighted mean exposure age of 25.7 ± 1.1 ka. This age represents the oldest cosmogenic data obtained for terminal moraine ridges in the Bavarian/Bohemian Forest. It is also older than the dated LGM moraines in other Central European Variscan ranges. In the Bavarian/Bohemian Forest, the age suggests an asynchronous stabilization of LGM moraines across the mountain range, which we attribute to differences in insolation of north- and south-facing sites. Additionally, the youngest preserved moraine, located at the mouth of the cirque, was deposited around 16.2 ± 0.6 ka.