Glacier Inventory for the Northern Patagonia Icefield, Chile, and Variations 1944/45 to 1985/86

The 28 outlet glaciers of the Northern Patagonia Icefield, Chile, with a total contiguous surface area of about 4200 km2, were inventoried in a detailed statistical manner. The San Quintin and San Rafael glaciers, each with an area of about 760 km2, are the two largest. Equilibrium lines are estimated at elevations of 900 to 1350 m, separating the total area into an accumulation area of 2578 km2 and an ablation area of 1550 km2. The variation of 22 major glaciers between 1944/45 and 1985/86 was elucidated and an annual average rate of recession of up to 68 m yr~' was determined. One glacier showed almost no change at all, while the southwestern snout of the Reicher Glacier showed a net advance, although small. A decrease in accumulation in the icefield has caused this general recession. However, the individual variation was probably governed by one of or a combination of the following four factors: (1) orographic situation of the accumulation area, i.e., whether it is located on the leeward (eastern) or windward (western) side; (2) the relative height of the topographic threshold to the icefield surface elevation; (3) the perimeter length, although in a relative sense, of the wasting front of the glacier; and (4) the ratio of the glaction area to the accumulation area of the glacier.