Crater Lake Area Field Trip: The Geology of Crater Lake National Park by Howell Williams

Since the time Williams published this work on the geology of Crater Lake National Park, radiocarbon dating of charcoal incorporated in the pumice flows revealed an age of about 6600 years for the eruption. This age has been further confirmed by radiocarbon dating of archeological sites at which Mazama ash was identified (Libby 1952; Rubin and Alexander 1960).

Recent studies on the distribution of Mazama ash show that it extends at least 600 miles (970 km) northerly from its source and more than 500 miles (800 km) to the east. This corresponds to a minimum area for the ash fall of about 350,000 square miles (900,000 kmZ) (Powers and Wilcox 1964; Fryxell 1965).

A detailed bathymetric survey of Crater Lake was made in 1959 by the U.S. Coast and Geodetic Survey. Byrne (1962) prepared a bathymetric chart from the survey data and described some of the underwater features. His chart and text are reprinted herein.