Geology of Crater Lake National Park

Crater Lake is a geological laboratory par excellence, for here we find an immense mountain (the hypothetical Mount Mazama) dissected for us, and its core displayed.

The cataclysmic eruption of Mount Mazama 7,700 years ago began with a towering column of pumice and ash, as depicted in Paul Rockwood’s painting. NPS image

Here we have revealed to us all the evidence necessary to reconstruct the processes which formed Mount Mazama, and the clues to the activity of vulcanism and glaciation.

As the Grand Canyon gives an unequalled calendar to the entire history of sedimentary processes upon the North American continent, so Crater Lake Rim exposes the history of the more recent volcanic forces, which so appreciably altered the topography of the Northwest.[Crater Lake National Park as a Field for Scientific Research, Nature Notes From Crater Lake, Vol. 23, 1992]


Geology 101 – Geological Processes at work in Crater Lake National Park

Books about the Geology of Crater Lake


Articles about the Geology of Crater Lake

A Detailed Guide to Geologic Features


A Geologic History of the Park 1912 by J.S. Diller, USGS


More Geology Pages in the Library
Crater Lake Geology in the News
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