The loneliest volcano in Alaska
By NED ROZELL
March 22, 2009
In 1905, Louis Prindle was a 40-year-old geologist bushwhacking
through eastern Alaska when he stumbled upon a crater covered
with spruce trees. He took a photo of the oddity and continued
on his wilderness trek to map the Fortymile country.
Mount Prindle, named for Louis by another geologist, is one of
the loneliest volcanoes in Alaska. While most of Alaska's volcanoes
make up the curve of the Aleutian Islands, with bunches of others
on the Alaska Peninsula, in Cook Inlet, and in the Wrangell Mountains,
Prindle stands alone in the Fortymile River country close to
the Canada border, about 50 miles northeast of Tok.
Mount Prindle, a dormant
volcano reaching more than 5,000 feet,
sits alone in Alaska's Fortymile country. Alaska has both a Mount
Prindle and a Prindle Volcano, both named for Louis Prindle.
This article refers to the volcanic mountain situated near the
East Fork River, close to the Canadian border. Mount Prindle
is located northeast of Fairbanks, in the White Mountains.
Photo by Ned Rozell
Louis Prindle's orders were to satisfy miners' demands for maps
of the upper Yukon and Tanana river regions. With hundreds of
miles to cover before ending his summer expedition in Fairbanks,
he didn't spend much time exploring the stadium-size volcano
tucked in the upper reaches of the East Fork River.
The volcano piqued the interest of others who followed Prindle,
including JB Mertie, another U.S. Geological Survey geologist
on a mapping mission. In 1931, Mertie wrote about "a little
volcanic cone, with a well-developed crater, which . . . is so
well preserved that it may well be of recent age."
Mount Prindle has a sharp-edged crater about 200 feet deep and
an open spout on one wall of the crater where lava flowed down
to the valley floor of the East Fork River. Spruce trees grow
inside the crater and tundra covers the outside wall of the volcano.
It still looks like a young volcano, though. One that the boreal
forest has not yet overtaken, and other geological forces have
not yet bulldozed.
Helen Foster of the USGS was part of a team that traveled to
the volcano in the 1960s. In an attempt to discover the date
of Prindle's last eruption, she noted a coating of volcanic ash
that blanketed the crater. The ash, known as White River Ash,
is from another volcano that erupted in the area about 1,900
years ago. From the ash coating and the dating of other rocks
she collected at Mount Prindle, she estimated that the volcano
was possibly several million years old, but might have last erupted
around the birth of Christ.
In 1995, another group of scientists chartered a helicopter from
Tok to study Mount Prindle. Ben Edwards of Dickinson College
in Pennsylvania was then a graduate student interested in the
volcano. Shortly after he and his party landed on the rim of
the volcano, Edwards picked up some green and white rocks that
make the volcano unique. The rocks, called xenoliths, are from
deep within Earth's mantle and crust, possibly more than 12 miles
down. When molten rock raced to the surface during Prindle's
eruption, it picked up xenoliths along the way and shot them
out as lava bombs that still rest on the surface around the volcano.
"We'd never get that information from drilling," said
Kelly Russell, Edwards' colleague at the University of British
Columbia. "Volcanoes like Prindle have erupted fast enough
and vigorous enough to bring this stuff
Mount Prindle belongs to a group of volcanoes in Canada called
the Northern Cordilleran Volcanic Province, Edwards said. This
band of dormant volcanoes extends from central British Columbia
all the way up to the Yukon Territory and Prindle in Alaska.
Russell and Edwards think Prindle and other volcanoes in the
group formed differently than Alaska's active volcanoes, which
sit above the subduction zone where the massive Pacific Plate
is grinding beneath the North American Plate. Though Prindle
is far from where the plates meet, the volcano is located in
an area where Earth's crust is stretched by the action of the
plates, Edwards said. This stretching creates fractures that
allow heat and molten rock to escape the inner Earth, erupt at
the surface, and sometimes leave behind solitary cinder cones,
such as Mount Prindle.
This column is provided
as a public service by the Geophysical Institute,
University of Alaska Fairbanks, in cooperation with the UAF research
Ned Rozell is a science writer at the institute.
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