Pumice Castle Overlook on the Rim Drive provides a view of one of the park’s most colorful features—a layer of orange pumice that has been eroded into the shape of a medieval castle. The pumice was deposited about 70,000 years ago during one of Mount Mazama’s most voluminous silicic eruptions. The source vent is beneath Cloudcap and immediately north of Pumice Castle. Other vents that erupted the dacite possibly vented to the northwest, within what is now the caldra. The dacite of Pumice Castle is present in the caldera wall from north of Devils Backbone east to Cloudcap Bay.

Credits and Sources:

"Crater Lake National Park Geologic Resources Inventory Report," National Park Service, http://www.nps.gov/crla/learn/nature/loader.cfm?csModule=security/getfile&pageid=666498 (accessed November 5, 2015).