 Shiprock, a volcanic neck with radiating dikes, NM |
 Sunset Crater, a cinder cone, near Flagstaff, AZ |
 Cross section of Pahoehoe flow, Hawaii Volcanoes National Park, HI |
 Pahoehoe Toe Outbreak, Hawaii Volcanoes National Park, Hawaii |
 (IG6) Columnar jointing in andesite lava flow, Devils Postpile State Park, CA |
 Mount Rainier, a composite cone, Mt. Rainier National Park, WA |
 Wizard Island, a cinder cone in a caldera, Crater Lake National Park, OR |
 Columnar jointing in a volcanic neck, Devils Tower National Monument, WY |
 Purcell sill, Glacier National Park, MT |
 Aa flow on pahoehoe flow, Hawaii Volcanoes National Park, HI |
 Basalt dike in granite, Acadia National Park, ME |
 Sag in tephra layers due to impact of block, Oahu, Hawaii |
 Cinder cone, Sunset Crater National Monuent, AZ |
 Columnar jointing, Devils Postpile State Park, CA |
 Pahoehoe lava flows at Kalapana Gardens, HI |
 Cinder cones in a large caldera, Haleakala National Park, Maui, HI |
 Laccolith, at Bear Butte State Park, SD |
 (IG20) Ubehebe Crater, a maar crater, Death Valley National Park, CA |
 (IG21) Edge of Newbury obsidian flow, Newbury State Park, OR |
 (IG22) Pahoehoe flow entering the ocean at Kalapana, HI |
 Pele's hair strands on pahoehoe lava, Hawaii Volcanoes National Park, HI |
 (IG24) Pillow lavas tilted on end and glaciated, Ontario, Canada |
 Pillow basalts near Pt. Reyes Station, CA |
 (IG27) Spatter rampart and spatter cone along a rift zone, Hawai Volcanoes National Park, HI |
 (IG28) Layers of a shield cone exposed in Waimea Canyon, Kauai, HI |
 (IG29) Pressure ridge in pahoehoe flow, Hawaii Volcanoes National Park, HI |
 Ash flow tuff deposits and fumarole remnants, Crater Lake National Park, OR |
 (IG31) Volcanic neck, Agathla Peak, AZ |
 (IG32) Andesitic volcanic dome, Mount Lassen National Park, CA |
 (IG33) Solidified lava lake in Keanakakoi pit crater, Hawaii Volcanoes National Park, HI |
 Fusiform volcanic bombs and blocks litter the surface at Haleakala National Park, HI |
 (IG35) Solfataras at the Sulfur Banks, Hawaii |
 Devils Backbone, a dike, Crater Lake National Park, OR |
 Sulphur crystals around the vent of a solfatara, the Sulfur Banks, Hawaii |
 Crater Lake, a caldera six miles in diameter, Crater Lake National Park, OR |
 Dike and volcanic neck, Ship Rock, NM |
 Baked zone (reddish layer) on tuff underlying a lava flow, Kauai, HI |
 Dikes cutting metamorphic rocks, Black Canyon of the Gunnison River National Monument, CO |
 Accretionary lapilli, ranging in size from 1/4 - 1/2 inch (6mm-12mm) in diameter, Oahu, HI |
 Block lava, Markagunt Plateau, Dixie National Forest, UT |
 Cow dung bombs on side of spatter cone, Hawaii Volcanoes National Park, HI |
 (IG46) Contact between granite (right) and granite pegmatite showing chill zone in pegmatite near Llano, TX |
 (IG47) Halemaumau crater within Kilauea Caldera, HI |
 (IG48) Llao Rock, a volcanic dome on the side of Mt. Mazama, Crater Lake National Park, OR |
 (IG49) Interior of composite cone showing layers of tuff and lava flows, Crater Lake National Park, OR |
 (IG50) Conglomerate consisting of lahar deposits, Piute County, UT |
 (IG51) Lava falls, Hawaii Volcanoes National Park, HI |
 (IG52) Granite of the Alabama Hills and Mt. Whitney of the Sierra Nevada batholith, CA |
 (IG53) Obsidian blocks at the base of a volcanic dome, CA |
 (IG54) Peles tears, glassy tear shaped bits of magma rapidly solidified in the air, HI |
 (IG55) Ropey pahoehoe, Hawaii Volcanoes National Park, HI |
 (IG56) Scoria, Hawaii Volcanoes National Park, HI |
 (IG57) Castle Geyser, Yellowstone National Park, WY |
 Grand Prismatic Spring, Yellowstone National Park, WY |
 (IG59) Grand Prismatic Springs runoff, Yellowstone National Park, WY |
 (IG60) Mudpots, Yellowstone National Park, WY |
 (IG61) Shield cones, Mauna Loa and Kilauea from Maui, HI |
 (IG62) Xenoliths of amphibolite and biotite schist in granite of the Vermillion batholith, near Orr, MN |
 (IG63) Kipuka, an area surrounded by lava flows, HI |
 (IG64) Lava tube with lava cicles, Hawaii Volcanoes National Park, HI |
 (IG65) Sinter forming along the edge of a hot spring, Norris Geyser Basin, Yellowstone National Park, WY |
 (IG66) Lava tree molds, Lava Tree State Monument, HI |
 Crisscrossing dikes in granite, Swift River, NH |
 (IG69) Rhyolite with blue quartz and pink K-feldspar, Llano, TX |
 (IG70) Pegmatite with large K-feldspar crystals surrounded by quartz, Lake Buchanan Dam, TX |
 Marchellina Mountain, a laccolith, Kebler Pass, CO |
 Aspens and block Lava Flow, Dixie National Forest, UT |
 (IG15) Dike swarm, Oahu, HI |
 Devil's Tower and Belle Fourche River, Devil's Tower National Monument, WY |
 Parallel dikes of basalt in granite, Schoodic Point, Acadia National Park, ME |
 Cross section of aa lava flows, Hawaii Volcanoes National Park, HI |
 Wiamea Canyon exposes the interior of a shield volcano on the Island of Kauai, HI |
 Haleakala cinder cones with shield cones in the distance, Maui HI |
 Layers of a cinder cone exposed by erosion, Red Mountain, AZ |
 Pahoehoe flow on the Island of Hawaii, Hawaii Volcanoes National Park, HI |
 Agathla Peak, a volcanic neck near Kayenta, AZ |
 Columbia River Plateau lava flows near Yakima, WA |
 Fusiform volcanic bomb approximately one foot (30 cm) long, Haleakala National Park, Maui, HI |
 Columbia River Plateau lava flows,Columbia River Gorge National Scenic Area, OR/WA |
 Dike cutting through Entrada Sandstone (Jr), Capitol Reef National Park, UT |
 Sill complex in Jurassic Entrada Sandstone, Capitol Reef National Park, UT |
 Ubehebee crater, a mar crater in Death Valley National Park, CA |
 Dike cutting through Granite along White Point Road at Aspy Bay, Nova Scotia |
 Aerial View of Shiprock showing volcanic neck and dikes, Shiprock, NM |
 First Light on Shiprock, NM |
 Mt St. Helens Twelve Years After 1980 Eruption WA |
 Mt. St. Helen's, Spirit Lake and blown down trees, Mount St. Helen's National Monument, WA |
 View of Mount St. Helen's from Norway Pass in 1981, Mount St. Helen's National Monument, WA |
 Tree trunks floating in Spirit Lake, Mt. St. Helen's National Monument, WA |
 Volcanic dome in the crater of Mt. St. Helens, WA |
 Shiprock: A volcanic neck and dikes looking northeast near Shiprock, NM |
 North Dome, Mono-Inyo Craters, CA |
 Lichen covered Volcanic Bomb, Peridot Mesa, San Carlos Apache Reservation, AZ |
 Devil's Tower, a volcanic neck, Devil's Tower National Monument, WY |
 Basalt Dike in Granite near White Point, Nova Scotia, Canada |