Images of Earth’s mountains from the International Space Station. NASA IMAGES
The Cascade Range includes many impressive stratovolcanoes along its north-south extent, some active during the past few hundred years. Mount Shasta in northern California is among the largest and most active (over the past 4,000 years) of the volcanoes in the Cascades. The summit peak stands at an elevation of 4,317 meters (14,160 feet) above sea level, and is formed by the Hotlum cone—the location of the most recently recorded volcanic activity (in 1786). Shasta’s summit is high enough to retain snow cover throughout the year, and several small glaciers are present along the upper slopes.
Immediately to the west of the summit peak (but still on the upper slopes of Shasta) lies the Shastina lava domecomplex, reaching 3,758 meters (12,330 feet) above sea level. Two dark lava flows that originated from the Shastina complex and flowed downslope (toward the northwest) are visible in the lower center of this image. The flows contrast sharply with the surrounding vegetated lower slopes and the barren upper slopes of Shasta. The Black Butte lava dome complex forms another isolated hill on the lowermost slopes of Shasta, near the town of Weed, California.
Geologists have mapped prehistoric pyroclastic flow and mudflow deposits (or lahars) from Hotlum cone and the Shastina and Black Butte lava dome complexes to distances of 20 kilometers (12 miles) from the summit of Shasta. As Mount Shasta has erupted within the past 250 years and several communities are within this hazard radius, the U.S. Geological Survey’s California Volcano Observatory actively monitors the volcano for signs of activity.
Mount Hood is located within the Cascade Range of the western United States, and it is the highest peak in Oregon (3,426 meters, or 11,240 feet ). The Cascade Range is characterized by a line of volcanoes associated with a slab of oceanic crust that is subducting, or descending underneath, the westward-moving, continental crust of North America. Magma generated by the subduction process rises upward through the crust and feeds a line of active volcanoes that extends from northern California in the United States to southern British Columbia in Canada.
While hot springs and steam vents are still active on Mount Hood, the last eruption from the volcano occurred in 1866. The volcano is considered dormant, but still actively monitored. Separate phases of eruptive activity produced pyroclastic flows and lahars that carried erupted materials down all of the major rivers draining the volcano. Gray volcanic deposits extend southwards along the banks of the White River (image lower left) and form several prominent ridges along the southeast to southwest flanks of the volcano. The deposits contrast sharply with the green vegetation on the lower flanks of the volcano.
The Mount Hood stratovolcano—a typically cone-shaped structure formed by layered lava flows and explosive eruption deposits—hosts twelve mapped glaciers along its upper flanks. Like other glaciers in the Pacific Northwest, the Hood glaciers have been receding due to global warming, and they have lost an estimated 61 percent of their volume over the past century. The predicted loss of glacial meltwater under future warming scenarios will have significant effects on regional hydrology and water supplies.
A clear summer day over Washington state provided the International Space Station crew the chance to observe Mt. Rainier—a volcano that overlooks the Seattle metropolitan area and the 2.5 million people who live there. In addition to its presence on the Seattle skyline, Mt. Rainier also looms large among volcanoes in the United States.
It is the highest volcano in the Cascades, with an elevation of 4,392 meters (14,411 feet) above sea level at the summit of the Columbia Crest. Emmons Glacier on the eastern slope is the largest glacier in the lower 48 states. Nisqually Glacier has been actively monitored for more than a century, making it the longest-monitored glacier in the United States. Rainier is an active volcano located next to a large population center, supports several large glaciers, and presents the largest volcanic hazard in the country. While the last recorded eruption of Rainier occurred in 1840, the volcano is continuously monitored by the U.S. Geological Survey’s Cascade Volcano Observatory.
This view shows off Rainier’s spectacular landforms, including details of the approximately 400-meter-diameter (1,280-foot) summit crater and the glaciers that radiate from the summit. The large debris fields that fill the valleys draining the glaciers comprise one of Rainier’s geohazards: potential landslides and debris flows triggered by earthquakes, eruptions, magma-water interactions, or sudden snow or ice melting. Also visible are roads leading to Paradise, an area on the mountain’’s south side that provides ready access to trails and spectacular vistas of the glaciers.
Mt. Everest is the highest (29,035 feet, 8850 meters) mountain in the world. This detailed look at Mt. Everest and Lhotse is part of a more extensive photograph of the central Himalaya taken in October 1993 that is one of the best views of the mountain captured by astronauts to date. It shows the North and South Faces of Everest in shadow with the Kangshung Face in morning light. Other major peaks in the immediate area are Nuptse and Bei Peak (Changtse). The picture was taken looking slightly obliquely when the spacecraft was north of Everest. Everest holds a powerful fascination for climbers and trekkers from around the world. The paths for typical North and South climbing routes are sketched on this image.
Much of the regional context can be seen in the complete photograph, which shows Mt. Everest and other large peaks to the northwest. More information on the photograph STS058-101-12 can be found at the Gateway to Astronaut Photography of Earth. An unannotated version can also be downloaded. The digital images shown have been reduced to a spatial resolution equivalent to 48 m / pixel; a high-resolution digital image of the same photograph would be at 12 meters per pixel.
A new interactive tutorial, Find Mt. Everest From Space, is now available on the Web. The presentation was created by the Earth Sciences and Image Analysis Laboratory, Johnson Space Center, from astronaut training materials developed by William R. Muehlberger (University of Texas, Austin), who has instructed astronauts in geology since the Apollo missions. While circling the globe every ~90 minutes, astronauts have only seconds to find key peaks in the Himalayas. These photographs are used to train their eyes so they can rapidly find and photograph Everest when they pass over. The tutorial features astronaut photographs of the Himalayas, interactive graphics that illustrate key geographic features for locating Mt. Everest, and. information on the geology of the region. The lesson concludes with a test of your ability to identify Everest in different photographs taken from the Space Shuttle.
Earth Sciences and Image Analysis Laboratory, Johnson Space Center
The Alps form a crescent stretching from the Mediterranean coasts of Italy and France to Vienna, Austria. On January 17, 2011, clear skies afforded the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’sTerra satellite an uninterrupted view of the mountain range. This natural-color image shows snow-capped mountains interspersed with vegetated valleys. Clouds snake through valleys in the north and west, and a nearly continuous cloud bank fills the Po Valley in the south, but skies over the mountains are clear.
The Alps’s began forming tens of millions of years ago, when the African tectonic plate slowly collided with the European plate. The plate collision helped close the western part of the ancient Tethys Sea and lifted up the massive European mountain chain that persists today.
Across the Earth, some mountain ranges are gaining elevation through tectonic uplift, while others are losing elevation through erosion. A study published in Tectonophysics in 2009 found that the Alps are doing both. The actions of glaciers and rivers scrape away fine sediment, which is carried away by water and wind. As this happens, the mountain range loses weight, lightening the load for the Earth’s crust. So just as ice and water scrape off the top, deeper rock layers push up from below. In the Alps, these processes appear to be in equilibrium, keeping the mountain range at a near-constant elevation.
In the Alps region, the valleys have attracted as much scientific attention as the peaks. Over hundreds of thousands of years, advancing Pleistocene glaciers ground away massive quantities of rock, leaving broad, U-shaped valleys. In between glacial advances, rivers carved deep, V-shaped gorges in many valley floors. Geologists long differed about how the steep, river-carved gorges could persist once the glaciers re-advanced. Many thought each new advance would wipe out the underlying gorge, and that the gorges seen today must have been carved since the last glacial episode ended.
Mount Kilimanjaro is a dormant stratovolcano and the highest mountain in Africa. Kibo Summit (5,893 m) at the top of Kilimanjaro is one of the few peaks in Africa to retain glaciers. The top image above is a high oblique photograph taken from the International Space Station in early April 2003. That photograph provides a 3-dimensional perspective on the positions of the glaciers on the upper northwestern and southern flanks of the mountain. The bottom photograph, taken from the International Space Station in late June 2004, shows large glacier fields (blue-white, with defined edges) on the northwestern and southern slopes of the peak. In this scene, a light layer of snow brightens the dark brown terrain around the glaciers.
Scientists use ice cores, an automated weather station, computer modeling, and images like these as tools to learn about the past and present activity of Kilimanjaro’s receding glaciers. One atmospheric scientist at the University of Wisconsin-Madison found clues that link reduced cloud cover to post-1880 decreased water levels in East African lakes. Lake evaporation indicates a decrease in both precipitation and cloudiness around Kilimanjaro. These two images illustrate the changes over time in snow cover at the summit as well as the current extent of the glaciers themselves. Light brown outwash channels from the northwestern flank icefield are particularly evident in the oblique photograph (top). While clear conditions over Kilimanjaro allow for the collection of spectacular images like these, the lack of cloud cover may be a cause for the glaciers’ retreat. Reduced cloud formation over the summit leads to reduced precipitation of snow cover on and around the icefields. This is turn reduces the reflectivity of solar energy from the summit, leading to increased thermal warming and melting of ice.
Most scientists agree that the glaciers of Mt. Kilimanjaro will be gone by the year 2020, but there is less agreement as to why they are now receding. Climatologists are now studying current weather trends, environmental changes from the late 1800s, and historical records of the mountain climate compared with longer-term climate records at lower elevations. Use of the ice core data together with ongoing meteorological data collection at the summit may help further refine models (and understanding) of the glaciers’ retreat. The loss of Kilimanjaro’s permanent ice fields will have both climatological and hydrological implications for local populations who depend on access to melt water from the ice fields as a source of fresh water during dry seasons and monsoon failures.
The Caucasus Mountains form a long (more than 1200 km) and steep spine connecting the Black Sea to the Caspian. Mt. Elbrus, the summit of the Caucasus Mountains, is located in southern Russia just north of the Georgian border, and is distinguished as Europe’s highest peak (5642 m). Elbrus is also an ancient volcano, although it has not erupted for nearly 2000 years. Elbrus’ profile comprises two volcanic peaks (East and West). They are popular trekking and mountain climbing destinations’the saddle between them provides access to the region.
In mid-September, the Russian and American crew aboard the International Space Station viewed Mt. Elbrus’ glaciated landscape as part of a study by Russian glaciologists. Elbrus is located west of the recent glacier slide on Mt. Kazbek, another giant peak in the Caucasus Mountains.