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Geomorphological mapping, sedimentology, lichenometry and dendrochronology were used to assess the nature and timing of glacier recession, moraine development and catastrophic mass movements in a tributary of the Leones valley, east of the Hielo Patagónico Norte, Chile. We show that during the 'Little Ice Age' Glaciar Calafate advanced downvalley to produce a terminal moraine. Recession of the glacier from this position occurred in the 1870s and produced a moraine dammed lake. In late 2000 a large rockfall into the lake breached the moraine and triggered a glacial lake outburst flood (GLOF) that entrained and subsequently deposited some 2 × 106 m3 of material. We interpret this event as a delayed paraglacial response to the retreat of Glaciar Calafate during the twentieth century. [ABSTRACT FROM AUTHOR]

Glacial geologic evidence and radiocarbon-dated glacial deposits provide evidence of glacier fluctuations during the last 5 ka years in the Andes. Radiocarbon-dated moraines, morphological and stratigraphical studies permit the reconstruction of glacier fluctuations during the Holocene in the Valenzuela area of the Mendoza Andes valley located at 35°S, in the upper Río Grande basin. The Holocene record in this part of the Andes is mostly unknown, so this research is relevant for palaeoclimatic reconstructions in South America. In the Río Valenzuela, glacier variations were dated in the El Azufre and El Peñón valleys. The first Neoglacial advance occurred at c. 5700 yr BP and a very close re-advance of similar magnitude occurred at 4700–4300 yr BP which formed well-preserved lateral-terminal moraines. The first Neoglacial advance occurred in the El Peñón valley at c. 4400 yr BP and a well-preserved terminal moraine is observed. A second Neoglacial advance reached its maxima at c. 2500–2200 yr BP in the El Azufre and El Peñón glaciers. A third, corresponding to the 'Little Ice Age', culminated at c. 400 yr BP (c. AD 1451–1641 cal. yr) and 350±60 yr BP (c. AD 1460–1644 cal. yr) in the El Azufre valley. The third Neoglacial advance is distinguished in the El Peñón valley based on morphological characteristics, colour, freshness of the glacial deposits and the proximity to the active glacier. It is indicated by the Amarilla I, II, III lateral moraines. An estimation of the magnitude of snowline depression is obtained comparing the altitude of the present snowline with that of the reconstructed snow line for the first Neoglacial and 'Little Ice Age' advances. [ABSTRACT FROM AUTHOR]