| At least 22 layers of tephra--volcanic ash and coarser airfall pyroclastic debris--can be recognized among the postglacial deposits in Mount Rainier National Park. Each of these tephra layers records a separate eruptive event. Eleven of the layers were erupted from Mount Rainier; 10 originated at Mount St. Helens volcano 80 km (50 miles) south-southwest of Mount Rainier; and the other came from prehistoric Mount Mazama at the present site of Crater Lake, Oreg., 440 km (275 miles) south of Mount Rainier. -- Mullineaux, 1974 |
