Breaking Through the Crust

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Science  05 Apr 2002:
Vol. 296, Issue 5565, pp. 15
DOI: 10.1126/science.296.5565.15b

The largest known volcanic eruptions in North America during the past several million years have come from the Yellowstone Plateau (YP) system. Activity began about 16 million years ago in eastern Oregon (yellow, solid borders) and progressed east northeastward, to the current location in western Wyoming (magenta), in a series of major eruptions thought to mark the trace of a hot spot in the mantle beneath North America. These eruptions have spread ash over most of the western United States.

Perkins and Nash used samples of this ash record from numerous localities to analyze the eruption history. In all, 142 major eruptions are recorded that can be separated into three broad sequences. Overall, the magma temperature and frequency of eruption (both of which may be driven primarily by the input of mantle-derived basalt) and migration rate (currently 22 kilometers per million years) all have declined over time, and these factors taken together with mantle-crust interactions could explain the history of eruption volumes.—BH

Geol. Soc. Am. Bull. 114, 367 (2002).

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