The Impact of Glacial Development on the Landscape of the Sierra Nevada

Abstract

The Sierra Nevada was the southernmost massif in Europe hosting glaciers during the Quaternary. The remains of those ice masses disappeared in the middle of the twentieth century. The Pleistocene glaciers in the Sierra Nevada remained confined to the high mountains, occupying the headwaters of ravines, with maximum lengths of 6–9 km. During the last decade, Cosmic-Ray Exposure (CRE) dating has complemented previously known geomorphological evidence, shedding new light on the chronology of various phases of glacial expansion and retreat. A moraine development phase occurred prior to the Last Glacial Cycle, around 130 ka, although most depositional and erosive records of glacial origin have been dated to the Last Glacial Cycle. This phase recorded two maximum advance pulses, the first around 30 ka and another of very similar extent at 20–19 ka. Later, the glaciers retreated significantly until they advanced again during the Oldest Dryas (17–16 ka). Then, after the almost total disappearance of the ice masses in the Sierra Nevada during the Bølling–Allerød (15–14 ka), small glaciers were formed during the Younger Dryas (12–11 ka). These glaciers disappeared at the beginning of the Holocene (10–9 ka), generating rock glaciers in the recently deglaciated cirques. At the end of the Holocene, including the Little Ice Age (LIA, 1300–1850 AD), very small glaciers were formed in the shelter of the northern walls of the highest peaks (Mulhacén and Veleta). They disappeared at the end of the LIA, giving rise to incipient rock glaciers.