Crater Lakeby 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 gases- silica 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 history1. Precambrian schists and gneisses 2. Paleozoic and Mesozoic deposition of

sedimentary rocks3. Laramide Orogeny – mountains, faults4. Eocene volcanism5. Late Tertiary uplift, faulting, erosion6. Pleistocene volcanism – supervolcano7. Glaciation8. 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/yellowstone_rocks.htm

• http://volcanoes.usgs.gov/yvo/history.html

• http://lcc.ctc.edu/departments/natural_sciences/pictures/pics/YELLtuff/YELL_tuff1.xtm