Abstract

The central Patagonian Andes is situated in a zone containing persistent mid-latitude westerlies. This situation brings heavy and frequent orographic precipitation (more than 3000 mm a-1) on the west side of the main ridge, but little (less than 1000 mm a-1) on the lee side. The Patagonia Icefields, the largest temperate ice masses in the Southern Hemisphere are located in the area from the main ridge to the Pacific coast at present. But at around LGM, many outlet glaciers (ice lobes) extended to the areas around 300 km west from the ice divide, where is now under semiarid climate. On the ridges on the eastern margin of Patagonian Andes under semi-arid condition, number of rock glaciers including active ones have been identified. This study aims to clarify the spatial distribution of rock glaciers in this area based on areal photo interpretation and fieldworks. Rock glaciers in “the Dry Andes” in Chile and Argentina have been well studied (e.g. Brenning, 2005; Croce & Milana, 2002; Trombotto et al., 1997), and cryogenic landforms in Tierra del Fuego, in the southern Patagonia were reported by Valcarcel-Diaz et al. (2006). However, rock glaciers in the central Patagonia have been quite little studied except for the summary of fossil cryogenic landforms including fossil rock glaciers in Patagonia by Trombotto (2002).