The Last Glacial Cycle in the Luna headwaters, Cantabrian Mountains (León Province, NW Spain): a controvesial Issue

Abstract

The Cantabrian Mountains (NW Spain) developed small icefields and alpine glaciers during the Last Glacial Cycle. The Luna Valley, which spreads along the southern slope of these mountains and shows both glaciation styles, has been studied by several authors, with different results concerning the position of the glacier fronts during the maximum ice extent stage. Prominent moraine complexes, in the valley bottom, have been frequently interpreted to represent the lowest glacier fronts; some studies, however, attribute these moraine complexes to a recessional phase. In this work, geomorphological mapping based on visual inspection of aerial photograph and field surveys allowed the maximum glacier extent at this catchment to be reconstructed. Throrough fieldwork made it possible to identify small till patches and glacially transported clasts that in turn allowed us to infer the position of the glacier front during the maximum ice extent (S-I) at an altitude around 1110 m. After this maximum, three recessional stages (RS-I, RS-II, and RS-III) were identified, followed by a Tardiglacial stage characterized by rock glaciers. This basin shows similarities with the Porma Valley (also in the southern slope of the Cantabrian Mountains) with regard to terminus altitudes, absence of terminal moraines, and glacier length during maximum.