Images

Distribution of hydrothermal features in Yellowstone as a function of their pH (modified and updated from Nordstrom et al., 2009). There are two distinct groupings: one is more acidic, and the other neutral to basic.

Simplified geologic map of the Timber Hill basalt and underlying geology in the Sweetwater Hills. The Sweetwater Road is shown by red. Note the basalt flow generally rests on poorly cemented sediments of the Sixmile Creek Formation shown in orange.  Map by Jesse Mosolof (Montana Bureau of Mines and Geology).

Simplified map of the Wyoming Province—a craton composed of Archean-age continental crust. Archean- and Proterozoic-age rocks outcrop in many places within the Wyoming Province and are shown as dark grey blobs. The yellow blob highlights the location of the Hellroaring and Crevice plutons, a small portion of which are exposed in northern Yellowstone National Park.

Map of the northwestern U.S., showing the approximate locations of the Yellowstone hotspot volcanic fields (orange) and Columbia River Basalts (gray).  Boundary of Yellowstone National Park is shown in yellow.  Inset shows physiographic map of southwest Montana and central Idaho.

USGS scientists work to recover sediment cores from Henrys Lake, Idaho. (Left): geologists traverse frozen Henrys Lake with coring supplies. USGS photo by Sylvia Nicovich, March 30, 2023.  (Right) Geologists lower the corer into the lake through a hole augured through the ice. USGS photo by Chris DuRoss, March 31, 2023.

Frying Pan Lake (also called Waimangu Cauldron), in New Zealand, sits within Echo Crater, which formed during the 1886 eruption of Tarawera.  A hydrothermal explosion from the crater in 1917 resulted in the formation of the hot spring "lake" by 1918.

Isotopic composition of the primary volcanic groups of the Absaroka volcanic province (the Washburn, Sunlight, and Thorofare groups) and two volcaniclastic units, the Sepulcher formation and the Daly formation.

Map of the distribution of pH for thermal pools within Norris Geyser Basin, Yellowstone National Park.  Cool colors are acidic, and warm colors are neutral to slightly basic.  These data were collected and organized using Geographic Information System (GIS) tools. Map by Jefferson Hungerford and Kiernan Folz-Donahue, Yellowstone National Park.

Volcanic deposits associated with the Absaroka volcanic province along the eastern and northern boundaries of Yellowstone National Park. The left panel shows the spread of the Absaroka Volcanic Supergroup (AVS) throughout Wyoming and Montana.

Landsat 8 nighttime thermal infrared image of Yellowstone National Park from January 31, 2023. Satellite-based thermal infrared data show areas on the surface that are warmer versus cooler, and they can be used to estimate surface temperature and the geothermal radiative heat output from the Yellowstone magmatic and hydrothermal system.

An example of the repeating seiche—a long-period oscillatory wave that can be present on a lake—measured over the course of a day by the lake-level sensor at the Grant Village boat dock on the West Thumb of Yellowstone Lake. The plot shows a cyclic variation of about 2 centimeters that occurs numerous times during June 13, 2021.

Geology of the unconformity on Mount Everts in Yellowstone National Park.  Sketch at the top was made by geologist William Henry Holmes in 1878 and correctly identifies Cretaceous sediments overlain by much younger rhyolite rocks, including fine ash deposits (“tufa”).  The photo at the bottom shows the same outcrop as viewed from Mammoth Hot Springs (USGS

Images of an unnamed thermal feature in the Three River Junction thermal area in southwest Yellowstone National Park. A, WorldView-3 satellite image from September 2014. B, National Park Service (NPS) aerial photograph from 2017. Images A and B were acquired before the feature went largely dry in late 2019 or 2020. C, WorldView-3 satellite image from June 2020.

Pie diagram showing the chloride flux, in kilotons per year (kt/yr), measured in 2022, with percentages for the four major rivers (Madison, Yellowstone, Snake, and Falls rivers) that drain Yellowstone National Park. Figure developed by Baine McCleskey.

Map of Yellowstone National Park lakes, rivers, and streams, with colors indicating the amount of arsenic in the water.  The Maximum Contaminant Level (MCL) defined by the Environmental Protection Agency for arsenic in drinking water is 10 micrograms per liter (µg/L).  In the vicinity of major geyser basins, especially on the Firehole and Madison Rivers, a

3D rendering of the shear-wave-speed anomaly (ɗVS) below Yellowstone. Regions of strongly reduced shear-wave speed most likely indicate volumes of partially molten crust. Iso-surfaces (surfaces of constant ɗVS) are shown in increments of 5%.

Seismic data coverage of the Yellowstone region and example of seismic noise records. By cross-correlating signals of the background noise recorded at two seismic stations and stacking the signals over many days, useful seismic waveforms can be extracted.

Map of seismicity (red circles) in the Yellowstone region during 2022. Gray lines are roads, black dashed line shows the caldera boundary, Yellowstone National Park is outlined by black dot-dashed line, and gray dashed lines denote state boundaries.

Google Earth image of the north part of Lower Geyser Basin showing the site of the Fountain Hotel and nearby Leather Pool, which was tapped to provide a source of hot water for the hotel.

Graph showing the discharge (blue) and specific conductance (black) measured at the Gardner River monitoring station in Yellowstone National Park during the June 10–13, 2022, flood.

Map of southern Idaho and the Snake River Plain, showing the eastern (ESRP) and western (WSRP) parts of the geologic province. Map by Zach Lifton, Idaho Geological Survey.