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Erratics located on a cinder cone on the northeast flank of Newberry Volcano, Oregon.

Exposed rock ridges are thick Pleistocene lava flows that were confined between large glaciers. Glacier Peak, Washington, view north.

The orange layer just below geologist's hiking pole is the Mazama ash (about 7700 ybp). Below that are glacial deposits. Above the Mazama is about a meter consisting mostly of fine-grained tephras from Glacier Peak, capped by soil and plants. That the tephras sit directly on top of the Mazama indicates that "Dusty" eruptions commenced about 7,000 years ago.

Geothermal ice cave at Mount Baker's summit formed by melting of a glacier due to increased heat from subsurface magma and fumarole on the surface expelling hot gasses.

Glacier Peak volcano, Washington reflected in pond below the Whitechuck Glacier, view from the south in late summer.

Guardian Geyser and Norris Geyser Basin, Yellowstone National Park.

Map of horizontal displacement vectors for Global Positioning System (GPS) stations in and around Mount St. Helens. Blue arrows show the direction and magnitude of horizontal movement, as measured at the GPS station from 2008-2014. The total horizontal displacement is indicated in millimeters (mm) and inches (in).

Impressive columns like these form along the margins of ice-confined lava flows but usually are eroded off the sides due to continued glacial movement after an eruption ceases. Columns are better preserved at the ends of the flows (this photo) where they are protected somewhat from the ice.

Lahar deposit cross section in the Trout Lake lowland, which originated from Mount Adams. Thickness of deposit is about 2.5 m (8 ft).

Tiltmeters allowed 24-hour monitoring as the information was telemetered back to CVO. Other instruments such as displacement meters for measuring cracks, seismometers for measuring earthquakes, gas sensors for measuring gas concentrations, and magnetometers for measuring the magnetic field, were also used for 24-hour monitoring.

Locations (Lat, Long, Depth) of January 17, 2010, earthquake swarm on Madison Plateau, Yellowstone National Park.

Mammoth Hot Springs at Yellowstone National Park, Wyoming.

Mount Adams viewed from the southeast in Klickitat Valley, Washington.

Mount Bachelor seen from South Sister across Sparks Lake. One of the "Devils Chain" domes visible in lower image foreground. Oregon

Mount Bachelor viewed from the south. Sparks Lake and South Sister visible in the background. Oregon.

Mount Bachelor's east facing ski slopes at sunrise.

Mount Baker's crater lake in 1976 formed due to glacial and snow melt as a result of increased heat from magma beneath the surface. Fumarole on left ejecting gas at a velocity of 268 kph (167 mph).

Mount Hood dominates the skyline outside of Portland, Oregon on a clear day. An major eruption of Mount Hood would pose a great hazard to the regional economy.

Mount Hood in the not-so-far distance beyond Downtown Portland, Oregon. Photograph taken at the top of the Portland Aerial Tram line on Marquam Hill.

Mount Scott Lookout seismic and GPS volcano monitoring station, view from the southwest. Near Crater Lake, Oregon.

Mount St. Helens prior to the catastrophic eruption of May 18, 1980. Streams and lava flows also visible. View is looking southerly from oblique aerial view. Mount Hood in distance.