America's Volcanic Past -
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| "Though few people in the United States may actually experience an erupting volcano, the evidence for earlier volcanism is preserved in many rocks of North America. Features seen in volcanic rocks only hours old are also present in ancient volcanic rocks, both at the surface and buried beneath younger deposits." -- Excerpt from: Brantley, 1994 |
Visit A Volcano - Alaska National Parks and Monuments
Learn More About Plate Tectonics and the "Ring of Fire"
For More Alaska Volcano Information
link to:
Alaska Volcano Observatory Website
Alaska:
Aleutian Arc:
Other Volcanoes:
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| Aniakchak National Monument |
Aniakchak Caldera:3
The Aniakchak Caldera, covering some 10 square miles, is
one of the great dry calderas
in the world. Located in
the volcanically active Aleutian Mountains, the
Aniakchak last erupted in 1911. The crater includes
lava flows, cinder cones, and explosion pits, as well as
Surprise Lake, source of the Aniakchak River, which
cascades through a 1,500-foot gash in the crater wall.
The site contains the Aniakchak Wild River.
| Bering Land Bridge National Preserve |
Bering Land Bridge National Preserve:4
The Preserve was established in part to preserve significant volcanic
features which are rare in the Arctic.
The Preserve contains extensive lava flows and ash/steam explosion craters
now turned to lakes called maars.
Maar lakes were formed when magma rose to meet ground water and permafrost
ice, causing massive steam explosions. There are four maar lakes in the
Preserve, which are the largest craters of their type on the planet. Their
explosions have occurred over a time span of more than 100,000
years. The most recent happened 17,500 years ago
and buried the ice-age landscape with thick layers of volcanic ash.
Devil Mountain Lake:4
Devil Mountain Lake, an unusual double crater
maar lake is the largest maar lake on the planet.
Lost Jim Lava Flow:4
Located in the eastern part of the Preserve are a variety of volcanic
features. The Lost Jim Lava Flow and associated cinder cones were formed
less than 2,000 years ago. This rugged lava flow covers more than
100,000 acres and provides an opportunity to watch vegetation recapture
land that has been totally devastated.
| Katmai National Park and Preserve |
Katmai National Park and Preserve:5
The 15 active volcanoes that line the Shelikof Strait make Katmai National Park and Preserve one of the
world's most active volcano centers today. These Aleutian Range volcanoes are pipelines into the fiery
cauldron that underlies Alaska's southern coast and extends down both Pacific Ocean shores (the so-called
Pacific "Ring of Fire"). This Ring of Fire boasts more than four times more volcanic eruptions above sea
level than any other region in historic times.
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Novarupta and the Valley of Ten Thousand Smokes:5
The June 1912 eruption of Novarupta Volcano altered the Katmai area dramatically. Severe earthquakes
rocked the area for a week before Novarupta exploded with cataclysmic force. Enormous quantities of hot,
glowing pumice and ash were ejected from Novarupta and nearby fissures. This material flowed over the
terrain, destroying all life in its path. Trees up slope were snapped off and carbonized by the blasts
of hot wind and gas. For several days ash, pumice, and gas were ejected and a haze darkened the sky over
most of the Northern Hemisphere. When it was over, more than 40 square miles of lush green land lay
buried beneath volcanic deposits as much as 700 feet deep. At nearby Kodiak, for two days a person could
not see a lantern held at arm's length. Acid rain caused clothes to disintegrate on clotheslines in
distant Vancouver, Canada. The eruption was ten times more forceful than the 1980 eruption of Mount St.
Helens. In the valleys of Knife Creek and the Ukak River, innumerable small holes and cracks developed
in the volcanic ash deposits, permitting gas and steam from the heated groundwater to escape. It was an
apparently unnamed valley when the 20th century's most dramatic volcanic episode took place.
Robert Griggs, exploring the volcano's aftermath for the National Geographic Society in
1916, stared awestruck off Katmai Pass across the valley's roaring landscape riddled by thousands of
steam vents. The Valley of Ten Thousand Smokes, Griggs named it.
Novarupta Dome:6
The nearly circular Novarupta Dome that formed during the
1912 eruption of Katmai Volcano, Alaska,
measures 800 feet across and 200 feet high.
The internal structure of this dome
-- defined by layering of lava fanning
upward and outward from the center -- indicates that it grew largely by
expansion from within.
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| Lake Clark National Park and Preserve |
Iliamna and Redoubt:7
Two active volcanoes, Iliamna and Redoubt, form an important link in the Pacific "Ring of Fire".
Venting steam, snow-capped, and rising more than 3,050 meters (10,000 feet), each is an impressive
volcano to be viewed from the eastern side of the park.
The Chigmits:7
Within the park the mountains of the Alaska and the Aleutian Ranges join. The Chigmits, an awesome,
jagged array of mountains, are the result of centuries of uplifting, intrusion, earthquakes, volcanism,
and glacial action.
| Wrangell-St. Elias National Park and Preserve |
Wrangell Mountains:8
The Wrangell Mountains, which form much of Wrangell-St. Elias National Park and Preserve,
are made up largely of thousands of lava flows that
have been erupted mostly from broad volcanoes during the past 26 million years.
This extensive volcanic terrain, which is called the
Wrangell volcanic field, covers about 4,000 square miles -
an area a little smaller than the State of Connecticut - and extends eastward from
the Copper River Basin through the Wrangell Mountains, into the
St. Elias Mountains of Alaska and the Yukon Territory of Canada.
All the volcanoes of the western Wrangell Mountains are less than 5 million years old
with the youngest lava flows are possibly as recent as 50,000 years ago.
The Wrangell volcanoes are among the highest mountains in North America and
some of the largest (by volume) in the world.
Mount Churchill:8
Large volumes of ash were deposited 1250 and 1890 years ago from the
eruption of Mount Churchill (the White River Ash).
Mount Wrangell:8
Most of volcanoes of the Western Wrangell mountains are unlike other volcanoes
located around the Pacific rim. Rather than erupting
explosive lavas forming steep-sided cones, they have been built by the accumulation of
hundreds of relatively fluid lava flows to form broad
mountains with gentle slopes, typical of shield volcanoes.
Now only youthful Mount Wrangell still
displays a shield-like form;
the other,
generally older volcanoes have had much of their superstructure removed by
glacial and other erosional processes.
Eruptive activity has been noted in Mount Wrangell in 1784, 1884-5, and 1900. On clear, cold,
and calm days, steam plumes are often visible.
Excerpts from:
1) USGS Alaska Volcano Observatory Website, January 2001
2) Kienle and Nye, 1990, IN: Wood and Kienle, 1990, Volcanoes of North America:
United States and Canada:
Cambridge University Press
3) U.S. National Park Service Website,
Aniakchak National Monument and Preserve, 2000
4) U.S. National Park Service Website,
Bering Land Bridge National Preserve, 2000
5) U.S. National Park Service Website,
Katmai National Park and Preserve, 2000
6) Tilling, 1985, Volcanoes:
USGS General Interest Publication
7) U.S. National Park Service Website, Lake Clark National Park and Preserve, 2000
8) U.S. National Park Service Website,
Wrangell - St. Elias National Park and Preserve, 2000
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