## 2 The Study Area  
Sierra Nevada forms part of the Betic Ranges and is a robust massif in the southeast of the Iberian Peninsula (Sierra Nevada, \(37^{\circ}03^{\prime}\) N; \(3^{\circ}21^{\prime}\) W; \(3100\) m) close to the Mediterranean Sea (Figure 1). Sierra Nevada is aligned in a west-east direction over more than 90 km and includes the highest altitudes of the Iberian Peninsula (Mulhacen, 3482 m; Veleta, 3398 m; and Alcazaba, 3366 m). Its basic structure is a succession of mountain chains of alpine origin over paleozoic crystalline rocks and triasic materials. Evolved forms predominate in its relief, especially summits and the adjacent southern slope. Also noteworthy is the generalized compartmentalisation by the organization of the fluvial network running into a tributary of the Mediterranean and Atlantic. Glacial imprints predominate in Sierra Nevada over 2500 m, while the periglacial morphodynamic does so at low altitudes [27; 28; 29; 30]. The vegetation cover at Sierra Nevada stands out for its richness in species and endemisms. This is due to the geographical position of the mountain, its altitude, and how the vegetation adapts to extreme climatic conditions. At high altitudes (over 2900 m), environmental conditions are characteristic of a periglacial zone: prolonged summer aridity, annual rainfall of 710 mm at altitudes of 2500 m, and an average annual temperature of close to 0 \({}^{\circ}\)C at an altitude of 3400 m [31]. The first studies of the Quaternary glaciarism of Sierra Nevada began in the middle of the 19 th century and have continued ever since [32]. As were other mountain nuclei of the Iberian Peninsula (Pyrenees and Picos de Europa), it was affected by the Little Ice Age (from the XVth century to the end of the XIXth), which would confirm that such a climatic pulsation with such slight repercussion on the modelling of the mountain similarly affected the extreme southwest of Europe. These were always small glaciers enclosed within the heart of old cirques. The glaciated areas are mainly included the gorges of the northern facade of the Sierra and, to a lesser extent, probably the south facade too [28]. Corral del Veleta forms part of the head of the Guarnon cliff. It is situated in the northern face of Sierra Nevada at the foot of the Picacho del Veleta (3392 m) between the Cerro de los Machos (3374 m) and the crest of Los Lastrones. As a whole, it forms an oval-shaped basin open to the northeast styled in banks of feldspathic mica schists of differing nature and resistence [27; 33]. Its base, which is inclined towards the west, coincides with a structural shelf full of clasts which enters into contact with the vertical wall of the Picacho del Veleta in a southern direction, and towards the north with a thick morainic front and side range that isolates it from the valley. The Corral del Veleta has a length (W-E) of over 600 m and a width (S-N) that varies between 175 m and 250 m. Its altitudinal difference is 300 m, with its lowest altitude at 3050 m (Figure 2a). The orientation and altitude of the Corral del Veleta enabled the formation of the glacier during the LIA and its duration until very recent times. At the end of the 19 th century, the basin was still full of ice and snow masses and partially so until well after the middle of the 20 th [34; 35]. There is no longer any visible trace of the glacier, although ice patches or snowdrifts remain from the late snowmelt at its base and small permanent ice plates trapped within its walls. The presence of these frozen bodies, together with the previously described glacial ice and permafrost buried under detritic material from the deglaciation process, explains what the glacier must have undergone and how, once enclosed in its basin, it was characterized by a successive evolution from white glacier to black glacier, and from this to fossil glacial ice and permafrost [27; 28].