Icefields and outlet glaciers in Patagonia

Two large ice-covered regions occur in Patagonia. The smaller one is called Hielo Patagónico Norte (Northern Patagonia Icefield: NPI) and is about 100km in length and 50km wide, located around 47°S (Fig. 46.1). The larger one is called Hielo Patagónico Sur (Southern Patagonia Icefield: SPI), which extends for about 350km from 48°20' to 51°30'S along 73°30'W (Fig. 46.2). The total surface areas of the NPI and the SPI were first estimated as 4400 km2 and 13,500km2 (Lliboutry, 1956), and were amended later to be 4200 km2 and 13,000 km2, respectively, based on the 1974-1975 aerial photographs (Aniya, 1988) and the 1986 Landsat TM images (Aniya et al., 1992). Elevations of the central plateaux of the icefields range from about 800 m on the western side and about 1500 m on the eastern side. Several high nunataks (altitudes greater than 3000m) soar above the icefields, namely Monte San Valentín and Cerro Arenales (NPI), and Volcán Lautaro (SPI).

A number of glaciers discharge from the icefields in all directions. In the NPI, a total of 28 outlet glaciers were inventoried. Thirteen of these calve into proglacial lakes, and only San Rafael Glacier calves into a fjord. Among 48 outlet glaciers inventoried in the SPI, all but two glaciers calve into lakes on the east side and into fiords on the west side (Aniya et al., 1996).

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