Some Points of Volcanic Interest in Yellowstone National Park
http://volcanoes.usgs.gov/yvo/overview.html

U.S. Geological Survey


This U.S. Geological Survey website highlights a few of the many interesting volcanic features related to the Yellowstone volcanic system. Highlighted features include the Obsidian Cliffs, the Grand Canyon of the Yellowstone, Sheepeater Cliffs, and the Mesa Falls ash-flow tuff. An oblique overview map of the Yellowstone area shows the location of these features in relation to other prominent locations around the park.

This resource is referenced here:
Subject: Geoscience:Geology:Igneous and Metamorphic Petrology:Volcanology
Resource Type: Audio/Visual:Maps
Topics: Time/Earth History, Solid Earth, Earth surface
Focus on Yellowstone: Surficial geology and hydrology, Volcanism, Bedrock geologyKeyword: caldera