Rock glaciers and debris-covered glaciers in the Central Chilean Andes have changed over the last 50 years. The researchers studied a watershed that supplies drinking water to Santiago. They used photos and satellite images to track glacier changes. They found that the uncovered glacier area decreased by 44.7% from 1955 to 1996. The volume of glaciers also decreased by at least 3.9 million cubic meters of water. The debris-covered glacier had more melt-out depressions by 2008. The ground temperature varied with altitude, and only the highest site had frozen ground underneath.