The plain was formed by lahar deposits from several eruptions of Glacier Peak, to the southeast. The area remains in the volcano's lahar hazard zone and also lies on a fault line that last produced a major earthquake less than 500 years ago. Soil in The Darrington area is primarily composed of glacial sands and gravels that have deposits of various mineral ores, including gold, silver, copper, lead, zinc, antimony, arsenic, mercury, and iron.