Background Information

Here are just a few links and references to introduce you to the volcanic histories of Yellowstone and Crater Lake National Parks.


  • Geologic Map of the Yellowstone Plateau Area. This geologic map shows rock formations, surficial deposits, faults, calderas, lava flows, and other geologic features of interest. A separate small map shows rhyolite flows. (more info)
  • Volcanic History of the Yellowstone Plateau Volcanic Field. This U.S. Geological Survey website gives an overview of Yellowstone volcanism. Text, numerous photos, tables, a map, and a volcanic term glossary explain the three major volcanic cycles that created the landscape that we call Yellowstone. (more info)
  • Yellowstone Volcano Observatory. This source is a clearinghouse of scientific information about the Yellowstone volcanic system. Topics include recent seismic and thermal activity, volcanic history, references and maps, a photo gallery, and FAQs. This website contains both general information that would be useful for anyone that is seeking information on the Yellowstone volcanic system, as well as more specific resources for geology students or teachers. (more info)

Crater Lake

  • Crater Lake Data Clearinghouse. This site provides a gateway to information and data pertaining to the Crater Lake geoecosystem. A wealth of digital data as well as scientific and general information is provided. ( This site may be offline. )
  • Mount Mazama and Crater Lake: Growth and Destruction of a Cascade Volcano. This fact sheet from the U.S. Geological Survey summarizes the geologic story of Mount Mazama and Crater Lake caldera. Possible future geologic activity and recent studies of the caldera floor beneath the lake are also discussed. Links are provided to other sources of information about Crater Lake, other Cascades volcanoes, and volcanic hazards. (more info)
  • Summary of the Eruptive History of Mount Mazama. This site features a detailed table, excerpted from a paper by Charles R. Bacon (USGS), summarizing the volcanic history of Mount Mazama and Crater Lake Caldera, Oregon. Descriptions of the major volcanic units are given in reverse chronologic order together with their age, age control, and composition. (more info)