Based on geologic mapping and dating of minerals, we know that the Yellowstone caldera formed 631,000 years ago. But how did the caldera collapse? Observations and monitoring data from several caldera collapses at other volcanoes in the 20th and 21st centuries provide clues.

In the wake of articles by the National Parks Traveler and the Wall Street Journal, two U.S. senators are wondering why a private company is being paid millions of dollars to manage the website that serves as a national portal for accessing recreational activities on federal lands.

You can never have enough guides to the national parks.

On August 1, 1823, an English missionary named William Ellis visited Kīlauea caldera with his Hawaiian guides on a tour of the Island of Hawaiʻi. He and his missionary companions were the first Westerners to visit the summit of Kīlauea, and the book that Ellis later published includes the first contemporary written observations of Kīlauea’s eruptive activity.