Under the Hood
Mount Hood last erupted more than 200 years ago, but at Crater Rock, not far from the summit, the signs of volcanic activity are unmistakable. Gas vents and hot springs emit sulfur fumes. Vapors rising from deep under the mountain carve snow caves, which can seem like sanctuaries for climbers but often hold deadly concentrations of CO2 and other gases. Rocks fall frequently from the steep unstable cliffs of the partially collapsed crater.