Images

Comparison of (a) 1904 Historical map with (b) 1988 USGS map. Colloidal Pool is a large, labeled pool roughly located on a straight line between Hurricane vent and Whirligig Geyser on the 1988 map (b); this same transect on the 1904 map (a) shows no feature at that location (white circle).

Scanning electron microscopy (SEM) images of the Colloidal Pool colloids (images are a combination of backscatter and secondary electrons). The colloids are a mixture of clay particles, hydrated silica, alunite, and diatoms.

A branching root cast from grasses that grew on the ashy lahars deposited along the ancestral Missouri River system. Plant roots growing in calcareous soils made holes that were filled with calcite after the organics rotted away.  Photo by Rob Thomas, August 2021.

A view of White Mountain -- a deposit of the Heart Mountain detachment -- from the Sunlight Basin Road in Wyoming. Much of the evidence supporting the lamprophyre diatreme triggering mechanism theory for the landslide was gathered at White Mountain.

Site of the former Fountain Hotel in Yellowstone National Park.  Red arrows indicate the location of the pipe that ran through the meadow between Leather Pool and the site of the Fountain Hotel (yellow arrow). Yellowstone National Park photo by Annie Carlson, October 2021.

Interferogram created from data collected on September 22, 2020, and September 17, 2021, by the Sentinel-1 satellite system. Colored fringes indicate a change in distance (called range change) between the satellite and ground surface that is caused by surface deformation.

“Hey Bear” volcano, Wyoming, with Raggedtop Mountain in the background. Hey Bear volcano is a small scoria cone that is about 1.3 million years old and that erupted over Eocene (~50 million-year-old) rocks (noted by yellow dotted line). Photo by Matthew Brueseke, Kansas State University, August 2021, used with permission.

Typical exposure of tabular blocks of layered ash in a matrix of cross-bedded ash. The tabular blocks were deposited, rapidly hardened, and ripped up and transported downstream along the ancestral Missouri River system with another pulse of ash and water, forming the cross-bedded matrix.

Photograph of Twin Buttes in Lower Geyser Basin looking to the northwest, with Excelsior Geyser of Midway Geyser Basin in the foreground. Twin Buttes is a thermal kame that formed when glaciers covered the area, and hydrothermal activity below the ice led to melting and the deposition and cementation of glacial sediments.

Imperial Geyser, Lower Geyser Basin, Yellowstone National Park. USGS photo by Lauren Harrison, July 2021.

USGS scientists Laura Dobeck and Sara Peek carrying field equipment to set up a gas monitoring station in Yellowstone National Park. USGS photo by Jennifer Lewicki, July 13, 2021.

USGS Cascades Volcano Observatory Physical Science Technician Brian Meyers installs a data telemetry antenna on a volcano monitoring station at Mount St. Helens. A DOAS scanner is mounted above the flat-panel antenna at the top of the mast.

Photo of Mount Hood taken June 7, 2003. The fault-plane solution for the M 3.9 earthquake that occurred on June 5, 2021 is in the lower right corner. 

View of Monument Geyser Basin in Yellowstone National Park, with one of the silica spire "monuments" (from which the basin gets its name) in the foreground. USGS photo by Mike Poland, May 15, 2021.

Roaring Mountain, an acid-sulfate thermal area about 5 miles south of Norris Geyser Basin along the Norris-Mammoth road.  At times during the late 1800s and early 1900s, the sound of gas escaping from vents could be heard over a mile away, but today the thermal area is mostly quiet, although remains intensely hot with over 100 megawatts of geothermal radiative

Photographs of the two dominant rock types found on Mount Everts: the Everts Formation (photo by Natali Kragh, May 18, 2021) and the Landslide Creek Formation (photo by Emma Kerins, May 2021). Notice the difference in scale between these two units, indicated by the pencil and field book.

Washington State Governor Proclaims May 2021 as Volcano Awareness Month.

Thermal anomaly map of Yellowstone National Park, based on a Landsat 8 nighttime thermal infrared image from 9 January 2021.  The color ramp indicates the intensity of the above-background thermal anomaly for each thermal area.  Lakes are blue.  Yellowstone caldera and resurgent domes are outlined in black.

Section from the piston core YL92-1C, collected in south-central Yellowstone Lake. The core is viewed horizontally, with the top of core to the left. The core section shown is from 5.21–5.63 meters (17–18.4 feet) depth.

Beginning of Yellowstone-Snake River Plain hotspot track and resulting northeasterly path of the ancestral Missouri River starting about 16.5 million years ago.  Modified from Hyndman D.W., and Thomas, R.C., 2020, Roadside Geology of Montana, Mountain Press Publishing, 464 p.

Ngorongoro volcano, in Tanzania, east Africa, is a caldera that formed 2-3 million years ago.  The Ngorongoro Conservation Area is a UNESCO World Heritage Site and home to one of the densest concentrations of wildlife in Africa.  Satellite Image from CNES/Airbus via Google Earth.