Mid-Holocene glacial activity in the Pyrenees

Abstract

Radiocarbon dating of sediments from a bog at c. 2100 m in the Cirque de Troumouse provides the first reliable dating of Holocene glacier fluctuations in the Pyrenees. The oldest organic material in the bog provides a maximum date (5190 ± 90 BP) for moraines immediately downvalley, which are either Lateglacial or, more probably, Holocene in age. Bracketing dates on laminated glacioacustrine sediments in the bog indicate a Neoglacial event between 4955 ± 90 and 4654 ± 60 BP, which was probably contemporaneous with moraine ridges immediately upvalley. More recent Neoglacial events, as yet undated, are indicated by younger silt-rich sediments in the bog and two younger moraine sets on the cirque floor at altitudes of c. 2250-2350 m. 'Little Ice Age' events were more restricted in extent, and are recorded by younger moraines at c. 2360 and at c. 2650 m resting on and immediately below the cirque wall.