Mazama and Glacier Peak Volcanic Ash Layers: Relative Ages

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Science  12 Mar 1965:
Vol. 147, Issue 3663, pp. 1288-1290
DOI: 10.1126/science.147.3663.1288


Physiographic and stratigraphic evidence supports the regional correlation of two volcanic ash layers with extinct Mount Mazama at Crater Lake, Oregon, and Glacier Peak in the northern Cascade Range of Washington. A radiocarbon age of 12,000 ± 310 years confirms geological evidence that ash derived from the Glacier Peak eruption is substantially older than ash from the Mazama eruption of 6600 years ago.