Images

A wide array of phototrophic microbial community textures exhibited in an alkaline (pH ~8.5) hot spring outflow channel in the Biscuit Basin, including thick mats, toadstools, ropes, and pinnacles. The differences in color are due to pigments (chlorophylls, bacteriochlorophylls, and carotenoids) produced by phototrophic microorganisms.

Sapphire Pool, an alkaline (pH ~7.5) spring in the Biscuit Basin area of the Upper Geyser Basin, Yellowstone National Park.

Map of seismicity (yellow circles) in the Yellowstone region during 2019. Gray lines are roads, red line shows the caldera boundary, Yellowstone National Park is outlined by black dashed line, and gray dashed lines denote state boundaries.

Map panels showing the distribution of major caldera-forming ash-flow deposits from the three major caldera-forming eruptions on the Yellowstone Plateau Volcanic Field. Updated from Christiansen, 2001 (USGS PP 729-G) with new age information.

Color-coded map showing the range of helium isotope values across Yellowstone National Park. BC = Boundary Creek, GGB = Gibbon Geyser Basin, MHS = Mammoth Hot Springs.

Dan Dzurisin, of the Cascades Volcano Observatory, conducting a leveling survey at Newberry Volcano, Oregon, in 2002.

Sulphur Caldron -- an example of an acid-sulfate hydrothermal feature in Yellowstone National Park. Photo taken by Blaine McCleskey, September 2008.

View of Castle Geyser, near Old Faithful, in eruption, taken from the boardwalk, November 5, 2019.

This mountain meadow inhabiting species is generally distinctive in its long copious stem and leaf hairs and inflorescences with congested white to pinkish or light purplish flowering heads that are surrounded by very long stem leaves.

Alpine meadow near Two Ocean Pass on the Continental Divide just south of Yellowstone National Park.

Image of the north part of Yellowstone Lake with the smoke plume from the Brimstone Fire in the distance, acquired by the YVO webcam on September 2, 2019, at 2:05 PM MDT.

The Parting of the Waters, looking southeast. North Two Ocean Creek splits into Atlantic Creek, flowing to the left in the photo, and Pacific Creek, flowing to the right. The wooden sign indicates that it is 3,488 miles to the Atlantic Ocean and 1,353 miles to the Pacific Ocean.

Aerial view of the new thermal area, in the center left. The existing Tern Lake thermal area is the bright white patch of ground in the upper middle part of the image. West Tern Lake is in the lower right. Research conducted under NPS Geology Programs Milestones Permit 2016-9.

View from the ground of the new thermal area near Tern Lake in Yellowstone National Park. Research conducted under NPS Geology Programs Milestones Permit 2016-9.

Lower Falls of the Yellowstone River and the Grand Canyon of the Yellowstone, photographed during a helicopter flyover on August 19, 2019.

Old Faithful Geyser, as well as Old Faithful Inn and the Yellowstone National Park visitor center, as viewed from the lookout on Observation Point trail.

Old Faithful geyser visitor center, and visitor facilities as viewed from Observation point on August 18, 2019.

Map of Yellowstone National Park showing locations of thermal basins that host hot springs, geysers, and mudpots.  Dark green areas host alkaline-chloride fluids.  Yellowstone Caldera margin shown as bold dashed line.

View of the Cirque of the Towers in the Wind River Range, with Pingora Peak in the center. The Bull Lake and Pinedale glaciations carved this valley by steepening and smoothing its granite walls. Image captured while descending from Texas Pass. Image view is toward the southwest. USGS photo by Stanley Mordensky, August 2019.

A closeup of the head and mouthparts of the wetsalts tiger beetle, a voracious predator in Yellowstone. Photo by Robert K. D. Peterson, 2019.

Example of how the same rock type can look very different due to hydrothermal alteration. Left image is of the Lava Creek Tuff, which erupted during the formation of Yellowstone caldera 631,000 years ago, near Tower Junction.