The Wrangell Volcanic Field is a volcanic field stretching from eastern Alaska in the United States to the southwestern Yukon Territory in Canada . The field includes the four highest volcanoes in the United States, Mount Bona , Mount Blackburn , Mount Sanford , and Mount Churchill , all of which exceed 15,000 ft (4,600 m) in elevation. It formed as a result of subduction of the Pacific Plate beneath the North American Plate at the easternmost end of the Aleutian Trench .
16-723: The bulk of the Wrangell Volcanic Field lies within the Wrangell Mountains of Alaska, but the field also extends eastwards into the neighboring Saint Elias Mountains and the Yukon Territory . The east–west length of the field is over 200 mile (320 km), while the width reaches up to 80 miles (130 km) in the central Wrangell Mountains. The field includes numerous shield volcanoes , stratovolcanoes , caldera complexes, cinder cones , and extensive lava flows , which have erupted throughout
32-585: A massive shield volcano which has been active historically. The stratovolcano of Mount Churchill has had the largest recent eruptions, with two large-magnitude explosive eruptions in the last 2,000 years that blanketed most of the Yukon with volcanic ash (the White River Ash ). The volcanoes of the western Wrangell Mountains are less than 5 million years old with the youngest lava flows are probably as young as 50,000 years ago. The Canadian portion of
48-772: The Yukon Territory in Canada . The Wrangell Mountains are just to the northwest of the Saint Elias Mountains and northeast of the Chugach Mountains , which are along the coast of the Gulf of Alaska . These ranges have the combined effect of blocking the inland areas from warmer moist air over the Pacific Ocean . The inland areas to the north of the Wrangell Mountains are therefore among
64-674: The Canadian portion of the Wrangell Volcanic Field include: 62°01′38″N 143°37′18″W / 62.0272°N 143.6217°W / 62.0272; -143.6217 Wrangell Mountains The Wrangell Mountains are a high mountain range of eastern Alaska in the United States . Much of the range is included in Wrangell-Saint Elias National Park and Preserve . The Wrangell Mountains are almost entirely volcanic in origin, and they include
80-432: The buildup of hundreds of comparatively fluid lava flows to form shield volcanoes. Only the young Mount Wrangell still shows its shield-like form; the other, commonly older volcanoes have had much of their original form removed by glacial and other erosional processes, such as Rabbit Mountain and Felsite Peak , which are now eroded to form an outcrop . Major volcanoes of the Wrangell Volcanic Field include: Volcanoes of
96-490: The coldest areas of North America during the winter. The Wrangell Mountains include 12 of the 40+ Alaskan peaks over 13,000 feet (4,000 m) (see fourteeners and thirteeners ): Other prominent mountains include: The mountains are named after explorer, president of Russian-American Company , and admiral Ferdinand von Wrangel . American folk singer John Denver wrote a song, "The Wrangell Mountain Song", in reference to
112-540: The eruption of rhyolite pumice , White River Ash , from Mount Churchill near the head of Klutlan Glacier blanketed large areas of northwestern Canada with tephra some 2,000 years ago. Most of volcanoes of the Western Wrangell Mountains are not like the other volcanoes located around the Pacific Rim . Rather than erupting explosive lavas forming stratovolcanoes, they have been built by
128-730: The field is dominated by scattered remnants of upper Cenozoic subaerial lavas and pyroclastic rocks . Over large areas extrusive rocks lie in flat undisturbed piles on a Cenozoic surface of moderate relief. Locally, however, strata of the same age have been affected by a late pulse of tectonism, during which they were faulted , contorted into tight symmetrical folds, or overridden by pre-Cenozoic baserocks along southwesterly dipping thrust faults. Considerable recent uplift, accompanied by rapid erosion, has reduced once vast areas of upper Cenozoic volcanic rocks to small isolated remnants. Although no centers younger than late Miocene are known in Canada,
144-411: The most recent activity of the volcano. The flow was dated using radiometric methods. Observers have reported minor activity at Sanford, primarily vapor clouds or plumes from ice and rockfalls. Some reported incidents may have been orographic clouds , while others have been interpreted as avalanches . The majority of Mount Sanford above 8,000 feet (2,400 m) is covered by icefields, merging to
160-427: The mountain appear to be a lava dome filling a larger summit crater. Two notable events in the mountain's history include a large rhyolite flow which traveled some 11 miles (18 km) to the north east of the peak and has a volume of about 5 cubic miles (21 km ), and another flow which erupted from a rift zone on the flank of the volcano some 320,000 years ago. The second flow was basaltic in nature and marks
176-411: The past 26 million years. All of the higher peaks are less than 5 million years old, since the rate of glacial erosion is very high in this region of extreme snowfall and cold temperatures. Higher elevations of the field above 5,000 ft (1,500 m) are almost entirely covered in glaciers and icefields , especially on the windward southern side of the ranges. The field is named for Mount Wrangell ,
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#1732771917662192-637: The range. Mount Sanford (Alaska) Mount Sanford is a shield volcano in the Wrangell Volcanic Field , in eastern Alaska near the Copper River . It is the sixth highest mountain in the United States and the third highest volcano behind Mount Bona and Mount Blackburn . The south face of the volcano, at the head of the Sanford Glacier , rises 8,000 feet (2,400 m) in 1 mile (1,600 m) resulting in one of
208-480: The second and third highest volcanoes in the United States, Mount Blackburn and Mount Sanford . The range takes its name from Mount Wrangell , which is one of the largest andesite shield volcanoes in the world, and also the only presently active volcano in the range. The Wrangell Mountains comprise most of the Wrangell Volcanic Field , which also extends into the neighboring Saint Elias Mountains and
224-518: The south with that surrounding Mount Wrangell . The largest glacier on Sanford is the Sanford Glacier, whose source lies at the steep cirque that cuts into the south side of the mountain. The mountain was named in 1885 by Lieutenant Henry T. Allen of the U.S. Army, a descendant of Reuben Sanford (an American politician). Mount Sanford was first climbed on July 21, 1938 by noted mountaineers Terris Moore and Bradford Washburn , via
240-489: The steepest gradients in North America . Mount Sanford is mainly composed of andesite , and is an ancient peak, being mostly Pleistocene , although some of the upper parts of the mountain may be Holocene . The mountain first began developing 900,000 years ago, when it began growing on top of three smaller shield volcanoes that had coalesced. Although obscured by icefields , the uppermost 2,000 feet (610 m) of
256-582: The still-standard North Ramp route up the Sheep Glacier . This route "offers little technical difficulty" and "is a glacier hike all the way to the summit" but is still a serious mountaineering challenge ( Alaska Grade 2 ) due to the altitude and latitude of the peak. The base of the route is usually accessed by air, but landing near the mountain is not straightforward. On March 12, 1948, Northwest Airlines Flight 4422 crashed into Mount Sanford. All 24 passengers and 6 crew members were killed. The wreckage
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