The Amalia Glacier, to the east of the Sarmiento Channel in Bernardo O'Higgins National Park, is one of several glaciers along the channel. They are nature's great landscapers, formed when enough snow accumulates in flat or bowl-shaped areas that the weight compresses the snowfall into ice. The icepack is squeezed out as it grows and gets heavier, moving down inclines and sometimes grinding the earth to carve out entire valleys. Glaciers are said to "retreat" in summer as they begin to melt. Often, huge chunks of ice "calve" from a glacier and fall into the sea. Despite global warming, which is causing glaciers around the world to retreat, many of Patagonia’s glaciers are still growing and expanding.