Crater Glacier

Crater Glacier is a geologically young glacier on Mount St. Helens, in the U.S. state of Washington. It formed after the volcano's 1980 eruption and, because of its sheltered location inside the crater, grew rapidly while remaining unknown to the public for nearly 20 years. It once held ice caves within its smooth ice before the volcanic activity of 2004 to 2008 significantly altered its shape; officials at first named it Tulutson Glacier before settling on Crater Glacier as its official name. Despite continuing volcanic activity, the glacier kept advancing, and by mid-2008 it had grown to completely encircle the lava domes at the volcano's center, with new glaciers forming around it as well.