Crater Lake
by Kristin Gates
• John Hilman first named
Crater Lake “Deep Blue
Lake”
• This was changed to its
current name in 1896 by
John Sutton
• William Steel worked with
congress to establish this
area as a national park
• Crater Lake was
established as a national
park on May 22, 1902
• 183,224 acres; 287
square miles
• Crater Lake is located in the
South Western Corner of
Oregon in the Cascades
• The Western Cascades
developed in the mid to late
Tertiary and these original
mountains were eroded before
volcanic activity started
• This older range and the
younger High Cascades
developed because of the
subduction of the oceanic crust
beneath the North American
plate
• Crater Lake is the remnants of
Mt Mazama, a stratovolcano,
which collapsed during a
volcanic eruption
History of Mt. Mazama
Klamath Indians
believed what is today
Crater Lake was the
Battle Grounds between
Llao the chief of the
below world who lived in
Mazama’s interior, and
Skell, the Chief of the
Above World who lived in
Mt. Shasta in northern
California
History of Mt Mazama
• Mazama formed during the
Pleistocene due to Basaltic
Eruptions
• 400,000 years ago was
Oregon’s tallest mountain
(12,000 ft)
• During this time, a volcanic
vent system began to develop,
laying the ground work for
what would be a cataclysmic
eruption
• 20,000 year dormant period
• Good lava conditions for
trapping explosive gasessilica rich and viscous
History of Mt Mazama
• Holocene: Lao Rock Eruption ejected
pumice and ash
• Pyroclastic lava flowed down the slope
weakening the earth there
• 200 years later this area would be split in
half
• 6,850 years ago, the
largest explosion ever to
occur in the Cascades
took place
• Ash Clouds filled the sky
and ash flows rolled into
the valleys
• What is today known as
the pinnacles formed as
hot gases escaped from
the earth
• The main eruption lasted
between a few days to a few
weeks
• The magma ejected so quickly,
it left the upper part of the
magma chamber empty and
the summit cone shattered
which pushed even more
magma to the surface
• The Caldera walls collapsed
inward
• The material from the Caldera
backed up the venting volcano
and led to an explosion
(This eruption is said to be 42
times stronger than the 1980
Mt. St Helen’s shown here)
• The caldera is
believed to have been
created by a single
explosion that
occurred during this
eruption
• About 10-13 cubic
miles of the mountain
was displaced
• Smaller eruptions inside
the caldera occurred
later, building Wizard
Island
• Phantom Ship, which is a
fragment of an older
volcano, also rises above
the surface
• Beneath the lake there
are other features like the
Merrium Cone that rise
over 1,000 feet from the
Caldera floor.
• Today the Caldera rim is
about 8,000 feet above
sea level
• The highest point on the
rim is Hilliman’s Peak
which rises to 8,159 feet
• Subduction continues
beneath the cascades
which is creating slowly
rising magma.
• Eruptions are infrequent
but may occur again
Works Cited
• Diller, Joseph and Horace Patton. 1902. Crater
Lake National Park. Washington Government
Printing Office
• Harris, A.G., Tuttle, and S.D. Tuttle. 2004.
Geology of National Parks (6th edition). Kendall
Hunt Publishing Company, Dubuque, IA
• Harris, Stephen. 2005. Fire Mountains of the
West (3rd edition). Mountain Press Publishing
Company, Missoula, MT
• Kiver, E.P. and D.V. Harris 1999, Geology of US
Parklands (5th edition). John Wiley and Sons,
Inc., New York, NY
Yellowstone National Park
Wyatt Fereday
Fun facts
• Established: 1872, the first national park
• Area: 2,219,791 acres; 3468 sq. miles (about
the size of Connecticut)
• Best known national park
• Over 90% is in Wyoming, but contains tiny
strips in Montana and Idaho.
• Over 10,000 geysers, hot springs, mud pots
and fumaroles
• Most of the park is over 7,500 ft.
• Biggest high-altitude lake in North America
(Yellowstone Lake)
• Includes continental divide
Geologic history
1. Precambrian schists and gneisses
2. Paleozoic and Mesozoic deposition of
sedimentary rocks
3. Laramide Orogeny – mountains, faults
4. Eocene volcanism
5. Late Tertiary uplift, faulting, erosion
6. Pleistocene volcanism – supervolcano
7. Glaciation
8. Post Pleistocene uplift, erosion,
geothermal activity
Pleistocene super eruptions
•
•
•
•
•
Yellowstone resides over a hotspot
Erupts about every 600,000 years
Last eruption: 630,000 years ago
Erupted 240 cubic miles of debris
It formed yellowstone caldera (15,000 sq.
miles)
• Rhyolitic lava (silicic lava = rholitic rocks)
• Tons of tuff (lithified volcanic ash)
• Post eruption lava flows and deposition fill in
caldera
Yellowstone Caldera
Hotspot trail
View from top of Mt. Washburn
Tuff
Morning Glory
a mudd pot
a geyser
Mammoth Hot Springs
Geyserite
Obsidian cliff
Lower Yellowstone Falls
Issues
• Wolves reintroduced in 1994
• Huge numbers of visitors
• Accidents involving thermal areas
• Bears
• Earthquakes
• Fires
• Risk of monumental explosion
References
• Harris, A.G., E. Tuttle, and S.D. Tuttle. 2004.
Geology of National Parks (6th edition). Kendall
Hunt Publishing Company, Dubuque, IA, 882 p.
• http://www.geotimes.org/nov00/hotspot.html
• http://www.yellowstonetreasures.com/yellowsto
ne_rocks.htm
• http://volcanoes.usgs.gov/yvo/history.html
• http://lcc.ctc.edu/departments/natural_sciences/
pictures/pics/YELLtuff/YELL_tuff1.xtm