Research history on glacial geomorphology and geochronology of the Cantabrian Mountains, north Iberia (43–42°N/7–2°W)

Abstract

The study of glacial geomorphology in the Cantabrian Mountains, a mountain range that extends 460 km along the northern coast of the Iberian Peninsula (SW Europe), started late in the 19th century and continues nowadays with a growing number of research papers. However, the number and timing of glaciations remains poorly understood, partially due to the still limited number of numerical ages. Its southerly location and proximity to the Atlantic Ocean make this mountain range potentially sensitive to past climate fluctuations. This work updates the glacial knowledge evolution for the whole range, from the Queixa-Invernadoiro Massif to the Basque Mountains, reviewing: (i) the history of glacial research since the late 19th century; (ii) the methodological approaches applied to reconstruct both the spatial extent and timing of past glacial stages; and (iii) the main geomorphological and geochronological evidence reported until date, including glacial features attributed to the Last Glacial Cycle (last 120 ka) and previous glaciations. According to current knowledge, glaciers extended over the Cantabrian Mountains covering a total area of 3150 km2, showing asymmetric development conditioned by variations of the topographic configuration and moisture supply along the range. Available geochronology based on radiocarbon, optically stimulated luminescence and terrestrial cosmogenic nuclides suggests the occurrence of at least 2 glacial advances during the Last Glacial Cycle: (i) a glacial maximum stage that took place at a minimum age of 36–45 ka (Marine Isotope Stage 3) and (ii) a second glacial advance at 19–23 ka (MIS 2). In some areas the extent of the glacier tongues during the second glacial advance was comparable to previous glacial maximum and was followed by glacial retreat conditions with formation of recessional moraines. Asynchronous glacial maximum conditions have been reported only for the Castro Valnera (MIS 4, 3 numerical ages) and Queixa-Invernadoiro (MIS 6, 1 numerical age) massifs until now. Finally, geomorphological evidence reported in Picos de Europa has been attributed to prior glaciations and correlated to cold conditions recorded during MIS 12 and MIS 22 based on a very limited number of numerical ages.