Post-little ice age paraglacial processes and landforms in the high Iberian mountains: A review

Three Iberian mountain ranges encompassed glaciers during the Little Ice Age (LIA): the Pyrenees, Cantabrian Mountains, and Sierra Nevada. The gradual warming trend initiated during the second half of the 19th century promoted the progressive shrinking of these glaciers, which completely melted during the first half of the 20th century in the Cantabrian mountains and Sierra Nevada and reduced by 80% of their LIA extent in the Pyrenees. In these formerly glaciated environments, the transition between glacial and periglacial conditions results in an accelerated paraglacial readjustment, with very active geomorphic processes. Cirque walls generate a large amount of sediments through rock-falls and slides. LIA moraines, devoid of vegetation and composed of highly unstable sediments, are being intensely mobilized by slope processes. Inside the moraines, the shrinking of LIA glaciers favoured the development of buried ice patches, with permafrost-related landforms, small periglacial features generated by solifluction, and cryoturbation processes and remarkable hydrological changes. Present-day morphodynamics is mostly related to seasonal frost, though patches of permafrost have formed in contact with the buried ice, undergoing a process of degradation because it is not balanced with present-day climate. This is reflected in the occurrence of multiple collapses and subsidence of the debris cover where the frozen bodies sit. Next to the small glaciated environments in the highest Pyrenean massifs, there is a permafrost belt undergoing also rapid geomorphic changes. Based on the observed processes, we discuss spatio-temporal patterns of paraglacial readjustment in Iberian mountains and compare it with other midlatitude mountain environments.