Rusk Glacier is located on the eastern face of Mount Adams in the U.S. state of Washington. Starting at an elevation of over 10,200 ft (3,100 m) at just below The Castle, the glacier flows eastward down slope. A significant portion of the glacier is covered by rock debris and in the middle of the glacier, at about 9,200 ft (2,800 m), there is a small ice-free island of rock. The glacier terminates at about 7,500 ft (2,300 m) at its rock-covered moraine.