Water-filled potholes
Cauldron-like depressions called potholes are scattered around the upper reaches of the Black Rapids Glacier. They often fill with water over the summer, eventually draining on the surface or subglacially. They are left-over remnants of crevasses that formed during the 1936-1937 surge of Black Rapids. During the surge the glacier terminus advanced by about 3 miles and earned the nickname the "galloping glacier". Taken June 13, 2014.