USGS/Cascades Volcano Observatory, Vancouver, Washington

Geology of Interactions of Volcanoes, Snow, and Water:
Mt. Rainier, Washington

Debris avalanches, White River valley


About 5800 yrs ago the northeast slope of Mount Rainier collapsed as a great debris and snow avalanche. It transformed rapidly downslope into a gigantic mudflow known as the Osceola lahar. The lahar innundated White River valley and buried the area now occupied by the city of Enumclaw. From there it entered entered Puget Sound 52 miles (83 km) km from the volcano.

Frizzell, V.F., Tabor, R.W., Booth, D.B., Ort, K.M., and Waitt, R.B., 1984, Preliminary geologic map of the Snoqualmie Pass 1:100,000 quadrangle, Washington: U.S. Geological Survey, Open-File Report OF-84-693.

A finished color version of this map and pamphlet will soon be: Tabor, R.W., Frizzell, V.A., Jr., Booth, D.B., and Waitt, R.B., in press, Geologic Map of the Snoqualmie Pass 30 minute by 60 minute quadrangle, Washington: U.S. Geological Survey Miscellaneous Investigations Map I-24##.

For recent report on the seaward extent of Osceola lahar, including Tacoma urban area: Dragovich, J.D., Pringle, P.T., and Walsh, T.J., 1994, Extent and geometry of the mid Holocene Osceola mudflow in the Puget Lowland implications for Holocene sedimentation and paleogeography: Washington Geology, v. 22, no.3, p. 3-26.



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11/03/97, Lyn Topinka