evidence: The Northern Patagonian Ice Field (NPIF), centered near 47°S, 73.5°W, is the smaller of two remnant ice masses crowning the Andes Mountains of lower South America. The NPIF is a vestige of an extensive ice sheet that covered much of Patagonia just over a million years ago. Today, with its glaciers largely in retreat and only an area of 4,200 sq km, it is still the largest continuous mass of ice outside of the polar regions. Survival is based on its elevation (1,100 to 1,500 m), favorable terrain, and a cool, moist, marine climate. The ice field has 28 exit glaciers, the largest twoSan Quintin and San Rafaelnearly reach sea level to the west at the Pacific Ocean. Smaller exit glaciers, like San Valentin and Nef, feed numerous rivers and glacially carved lakes to the east.