Images

Color-shaded relief topographic map of the track of the Yellowstone hotspot showing the ages and locations of volcanic fields and faulting patterns which become younger to the northeast.  Areas in cooler colors (greens and blues) represent low topographic elevations, whereas warmer colors (oranges and reds) represent high elevations.  Adapted from

Apollinaris Spring in 1987.  The spring was modified in 1925 so that water would flow through pipes to be emitted from a rock wall.  Yellowstone National Park photo by Jim Peaco.

La Garita Mountain (elevation 4179 m [13711 ft]), Colorado.  The mountain is a resurgent block of Fish Canyon Tuff that is more than 1 km (0.6 mi) thick—the top is eroded and the base is not exposed.  The tuff formed during the eruption of La Garita caldera about 27.8 million years ago and has a volume of more than 5000 km³ (1200 mi³)

Mount Vesuvius behind city of Naples. The modern cone of Vesuvius is flanked on the left by Monte Somma, the rim of a caldera that formed about 17,000 years ago. Eight major explosive eruptions have occurred since, including the 79 CE eruption that destroyed Pompeii and other towns.

Novarupta Dome, with Falling Mountain and the upper valley portion of the Valley of Ten Thousand Smokes in the background.  Photo by Tom Miller, June 1979.

Muddy thermal discharge (foreground) near Congress Pool (middle ground) in Norris Geyser Basin following the June 30, 1975, magnitude-6 Yellowstone National Park earthquake,  NPS photo by Rick Hutchinson.

Map: Index map showing locations of 1967–1968 research drill holes in Yellowstone National Park. Taken from USGS Bulletin 1967.

Photo of damage to the Mammoth-Norris highway, just south of Mammoth Hot Springs, caused by the June 30, 1975, magnitude-6 earthquake.  Haynes Inc. photo for the Deseret News.

Gibbon River in Gibbon Meadows immediate following the June 30, 1975, magnitude-6 Yellowstone National Park earthquake.  The muddy color is due to increased sediment load.  NPS photo by Rick Hutchinson.

An example Correlation of Map Units chart from the Surficial Geologic Map of Yellowstone National Park (U.S. Geological Survey, 1972) that demonstrates a typical classification scheme for surficial units.

Shoshone Tukudika (Sheepeater) men, women, and children at Medicine Lodge Creek, Idaho, in 1871. This photo was taken by U.S. Geological Survey employee William Henry Jackson.  Courtesy of National Park Service, Yellowstone National Park, YELL 8151.

Seismic geyser in Yellowstone’s Upper Geyser Basin during an eruption. Based on the study of George Marler and USGS scientist Donald E.

Pearlette Ash in Comanche County, Kansas.  Kansas Geological Survey photo by Grace Muilenburg, April 1969 (https://chasm.kgs.ku.edu/ords/pubcat.phd2.View_Photo?f_id=3165).

Eruptions from drill rods during research drilling in Yellowstone National Park, 1967–1968. Left panel shows initial explosive eruption of water-steam mixture from open drill pipe in drill hole Y-5 (Rabbit Creek) on August 20, 1967.

Bob Fournier (left) and Don White (right) at the Y3 drilling site in Pocket Basin adjacent to Ojo Caliente, Lower Geyser Basin, Yellowstone National Park, in 1967.  USGS Photo.

The solubility of amorphous silica (solid silica with no crystal structure) in water as a function of temperature. When deep groundwater flows through hot rhyolite it can remove silica from the rhyolite (dissolve silica).

Kaleidoscope Geyser in the Lower Geyser Basin. George D. Marler and Donald E.

President Kennedy signs the nuclear test ban treaty for the United States in 1963. Photo from National Archives, Still Pictures Division, Department of State Collection 59-0, box 23 (https://nsarchive2.gwu.edu/NSAEBB/NSAEBB94/tb02.htm).

Top: the first thermal infrared images of Yellowstone (1961).  Warm areas are brighter; cold areas are darker.  These images were published in: McLerran, J.H. and Morgan, J.O. (1965) Thermal mapping of Yellowstone National Park.

View of Lower Geyser Basin. Note active thermal pools (Great Fountain Geyser) in the foreground with thermal grasslands—kept treeless by hot soils—and lodgepole pine forest in the distance. Photo by George Marler, 1959.

Aerial view of Black Opal Pool, Black Diamond Pool, and part of Wall Pool, all in Biscuit Basin, Yellowstone National Park, taken in 1959 sometime after the Hebgen Lake earthquake (which occurred on August 17 of that year).