CRATER LAKE NATIONAL PARK
GEOLOGIC RESOURCES MANAGEMENT ISSUES
SCOPING SUMMARY
Sid Covington
Geologic Resources Division
December 8, 2004
Executive Summary
Table of
Contents
A Geologic Resource Evaluation scoping meeting
for Crater Lake National Park as held in Ashland, Oregon, on Wednesday
afternoon, March 3, 2004. The scoping meeting participants identified the
following as the most significant geologic resources management issues.
- The potential for geothermal exploration
and development adjacent to the park has long been an issue.
- Water right rights and the drilling of a
water well has become a recent issue.
- Seismicity and geohazards monitoring and
study is needed.
- Paleolimnology – need to core the lake to
study bottom sediments.
Introduction
The National Park Service held a Geologic
Resources Evaluation scoping meeting for Crater Lake National Park (CRLA) in
Ashland, Oregon, Wednesday afternoon, March 3, 2004. The purpose of the meeting
was to discuss the status of geologic mapping in the park, the associated
bibliography, and the geologic issues in the park. The products to be derived
from the scoping meeting are: (1) Digitized geologic maps covering CRLA; (2) An
updated and verified bibliography; (3) A scoping summary (this report); and (4)
A Geologic Resources Evaluation Report which brings together all of these
products.
Crater Lake National Park was established on
May 22, 1902, by act of Congress (32 Stat. 202). Prior to this, the Crater Lake
was administered by the General Land Office as part of the Cascade Range Forest
Reserve. Total area of the park is about 183,224 acres.
The park has identified 56 quadrangles of
interest. Of these, the park covers the following twelve: Welch Butte, Pumice
Desert East, Pumice Desert West, Hamaker Butte, Thousand Springs, Red Blanket
Mountain, Union Peak, Maklaks Crater, Sun Pass, Pothole Butte, Crater Lake East,
and Crater Lake West. The remaining 44 maps extend coverage approximately two
quads out in all directions.
Geologic maps include: U.S. Geological Survey
Professional Paper 3 covering the park at a scale of 1:140,800 (Diller and
Patton, 1902); MF-1507a, scale 1:62,500 (Smith, 1983) which takes in the extreme
south end; and, Open-File Report 83-660, scale 1:167,000 (Sherrod and Benham,
1983) which covers the extreme northern part of the park. Three small scale
geologic maps (scale 1:250,000) cover portions of the park and the surrounding
quads of interest: Crescent (MacLeod and Sherrod, 1992), Klamath Falls, (Sherrod
and Pickthorn, 1992), and Medford (Page, Blakeley, and Cannon, 1983). South of
the park, Smith (1988) produced a geologic map at 1:62,500. A geologic map of
the Fort Klamath quad is available from the State of Oregon.
Charlie Bacon with the U.S. Geological Survey
(USGS) started mapping Crater Lake in 1979. The current geologic map is at a
scale of 1:24,000. It is wider (east-west) than the park boundary but not as
high (north-south) so some of the park is cut off. Strips on the northern end
and southern end of the park have not been mapped. The map includes both bedrock
and surficial geology and will be published as a Miscellaneous Investigations
Map ("I" map) by the end of 2004 or early 2005. The mapping is also based on
approximately 2,000 samples and about 100 radiometric age dates. Other products
include 11 panoramic drawings of the caldera wall as well as a "fantasy map" of
the bedrock. The work is in ArcInfo and can be made available to the park. A
USGS bibliography of the mapping will also be made available to the park. A
geochronology of Mt. Mazama will be published in a Geological Society of America
Bulletin after the map is released.
Bacon’s mapping work could be expanded to cover
the north and south portions to the same scale and detail. This could be
available by 2008. A goal is to obtain geologic coverage at least one quadrangle
beyond the boundary. Currently, USGS map MF-1528 is available as a surficial
reconnaissance map. Other work is in progress by the Oregon Department of
Geology and Mining include possibly a digital version of the USGS map I-1891
(1991, scale 1:125,000) of the northern part of the park by D.R. Sherrod. Other
quads in progress at 1:24,000 are Fuego, Wocus Bay, Soloman Butte, Applegate
Butte, Agency Lake, Chiloquin, and S’Ocholis Canyon. Helpful information for
Crater Lake geospatial data includes:
http://vulcan.wr.usgs.gov/Volcanoes/CraterLake/#
http://craterlake.wr.usgs.gov#
http://geopubs.wr.usgs.gov/i-map/i2790/#
http://vulcan.wr.usgs.gov/Volcanoes/CraterLake/Maps/map_mazama_general_geologic.html#
An NCRS soil survey has been completed. The
survey was done in 1999-2001. The survey is available on line at
www.or.nrcs.usda.gov. The survey includes ecological site descriptions. Other
derivative products include geospatial data and an accompanying manuscript and
an Access database. An ArcView extension has a soil data viewer which will help
resource managers with soil interpretation.
Physiography
Crater Lake National Park is located in the
Cascade Physiographic province. The Cascade Range is composed almost entirely of
volcanic cones, vents and lava flows. It extends north into southern British
Columbia - Mt. Garibaldi is the northernmost volcano - and south to Lassen Peak
in California, the southernmost volcano. In Oregon the crest of the range
averages about 5,000 feet, although the highest peaks are Mt. Hood at 11,360
feet, Mt. Jefferson at 10, 495 feet and South Sister at 10,354 feet (Baldwin,
1976). The highest volcanoes in the Cascade Range are Mount Rainier in
Washington at 14,411 feet and Mount Shasta just north of Lassen at 14,161 feet.
The USGS has identified 13 potentially active volcanoes in the Cascade Range of
the U.S. Pacific Northwest, 11 of which have erupted in the last 4,000 years and
7 in the past 200 years (Dzurisin, et. al.,1999).
The Cascades are divided into the Western Cascades and the High Cascades. The
Western Cascades are composed of older Tertiary (Late Eocene to Late Miocene)
flows, tuffs, and intrusives. The High Cascades include the high peaks such as
Mt. Hood, Mt. Jefferson, and South Sister that have erupted more recently.
Deposits are almost entirely late Miocene to Holocene age (Baldwin, 1976). The
eastern slope is steeper and more abrupt than the more gently sloping Western
Cascades.
At a maximum depth of 1,932 feet, Crater Lake is the deepest lake in the United
States, the second deepest in the Western Hemisphere, and the seventh deepest in
the world. Average depth is about 1,500 feet. The surface elevation is 6,176
feet and the highest point on the rim (Hillman Peak) is 8,056 feet. Wizard
Island is a small cone rising 764 feet above the surface of the water and has an
elevation of 6,940 feet. The highest point in the park is 8,926 feet at Mount
Scott, a parasitic cone from Mount Mazama, the volcano that formed Crater Lake.
Geologic History
The Cascades formed as a result of the
collision of the San Juan de Fuca plate with the North American plate, a
collision still in progress. The oceanic crust is being thrust under or
subducted beneath the North American crust. This subduction began in the Early
to Middle Tertiary as evidenced by the lava flows and pyroclastics of the
Western Cascades. Some of these volcanics have been given formational names such
as the Eocene Colestin Formation and the Little Butte Volcanics of Oligocene and
early Miocene age (Baldwin, 1976). The Colestin Formation consists mainly of
andesitic tuff, conglomerate, and tuffaceous sediments in the southern Oregon
Cascades. The Little Butte Volcanics consist of a variety of flows and tuffs
from 3,000 feet to 15,000 feet thick. Along the western margin of the Cascades
in the northern part of Oregon, the middle Miocene flood basalts of the Columbia
River overlie the Little Butte volcanics. Other volcanic formations of Middle to
Upper Miocene include the Sardine Formation, Rhododendron Formation and the
Boring Agglomerate (Baldwin, 1976). None of these formations are exposed in
CRLA, but probably form the foundation upon which the volcanoes of the high
Cascades are built.
By Late Miocene, as subduction continued,
volcanic activity shifted slightly eastward forming the High Cascades. In the
Pliocene, eruption of basalt and andesite flows built up lava plateaus upon
which Mount Mazama began to form. A small island in Crater Lake known as the
"Phantom Ship" is believed to be the remains of a small cone that formed in the
Pleistocene as a precursor to Mazama. Mount Mazama is a composite volcano or
stratovolcano; that is, it was built by alternating eruptions of lava flows
(mostly andesitic) and pyroclastics, along with abundant intrusive dikes and
sills. Mazama had a large number parasitic cones and flank eruptions represented
today by Mount Scott (Harris and Tuttle, 1983).
During the Pleistocene, glaciation developed as
Mazama began to grow. Much of Mazama was probably ice-covered during its
eruptive history. The caldera walls of Crater Lake display glacial deposits
interbedded with lava flows. The evidence indicates that there were several
episodes of glacial advance and retreat, the latter likely due to eruptions of
Mazama. Soil horizons with charred vegetation at the top of till deposits and
overlain by lava flows indicate that there were quiescent periods between
eruptions during which vegetation flourished.
Geomagnetic data indicate that most of the
lavas of the High Cascades were of normal polarity. Since the last reversal (to
normal polarity) took place about 700,000 years ago, most of the eruptive
activity has taken place since that time (Cranson, 1982). At its maximum height,
Mazama may have been over 12,000 feet and similar in size to Mt. Hood (Baldwin,
1976). Eruptions began to be more siliceous forming dacite domes, siliceous
flows, and dacitic pyroclastics. These eruptions tended to be from vents north
of the central vent: the vent of the Watchman andesite, the Hillman Peak cone,
the vents of the Llao Rock, Cleetwood, and Redcloud dacite flows (Harris and
Tuttle, 1983).
About 6,600 year ago Mount Mazama erupted a
huge amount of ash that spread over the entire Pacific Northwest, from southern
British Columbia and Alberta to northern California and Nevada, and east
covering most of Idaho and the western one-third of Montana. It is estimated
that 15 to 17 cubic miles of material was blown off the mountain. Mazama
collapsed into a caldera 5 miles wide and 4,000 feet deep (Harris and Tuttle,
1983). It has been estimated that the amount of material blown out of the
volcano plus the amount of lava that flowed out far exceeds the material of the
cone that was lost. The difference must have come from the magma chamber which
evacuated resulting in the collapse.
After this defining eruption, there was further
activity that resulted in the formation of Wizard Island and two smaller cones
on the caldera floor. Wizard Island rise about 2,600 feet above the caldera
floor but is only 774 feet above water level. The larger of the two smaller
cones, Merriam cone, lies near the southern edge of the caldera and, though
submerged, rises about 1320 feet from the caldera floor (Harris, 1980). The
accumulation of rain and snow resulted in the lake we see today.
Significant Geologic Resource Management
Issues at Crater Lake National Park
1. Geothermal Exploration and Development
There have been in the past, and likely will be
in the future, significant issues regarding the influx of geothermal waters into
the lake as well as the potential for geothermal exploration and development
outside the park. In 1986, California Energy Company Inc. put down two
geothermal test wells outside the park boundary, hitting steam at about 1,300
feet. The company had about 97,000 acres of the adjacent Winema National Forest
under lease and had planned to drill 24 sites, some within one-quarter mile of
the boundary. Although there was concern from the public that drilling may drain
the lake (highly unlikely), the major concern of the park was the potential
development of geothermal facilities in close proximity to the park. These
issues were of such concern that Congress singled out Crater Lake along with 21
other NPS units as needing special protection under Section 115 of the
Department of the Interior and Related Agencies Appropriations Act for 1987
regarding geothermal leasing. This resulted in major monitoring and research
efforts in the late '80s and early '90s. After the legislation was passed that
required NPS input into future leasing and drilling proposals, interest in the
area by Cal Energy and others declined. With the policy of the present
administration emphasizing energy development, including geothermal resources,
there still a potential for geothermal development to impact the park. The
Crater Lake research did indicate that there is some influx of water at slightly
elevated temperatures at the bottom of the lake. The concern now is that
drilling may change this geothermal flow regime.
2. Water right rights and the drilling of a water well.
The park has proposed drilling a water well in
the park. Although a water well would not tap geothermal waters, nonetheless,
since the park has opposed geothermal drilling, the local public believes that
this drilling should not be allowed either. There are also issues of water
rights as well. The park does have surface water rights, but groundwater rights
are questionable.
3. Seismicity and Geohazards
At present there is a low occurrence of
earthquakes, but Charlie Bacon believes that the area may be due for a magnitude
7.5+ quake. There is no seismograph in the park and coverage in the area is
poor. It may be possible to obtain an instrument from the USGS Volcano Hazard
Team. However, rockfalls are an issue since a visitor was killed by a rockfall
on the Cleetwood Cove Trail about 10 years ago. Help is needed to try to
stabilize this trail, the only tail down the caldera wall to the lake. Major
landslides into the lake could capsize tour boats, which are required to avoid
the most hazardous areas.
4. Paleolimnology
The CRLA staff expressed a strong desire to
study the sediments in the bottom of the lake. About two dozen 6-foot cores have
been recovered. The park would like to continue this project to study the
history of sedimentation, diatoms and other microfossils, and climatic history.
Funding is needed to continue this project.
5. Other Issues
Caves: There are over 40 caves in the park that have not been inventoried and
mapped. One cave was closed by the development of a road. There is a need for
research on bats and other fauna. The park should work with the National
Speleological Society (NSS) to develop a program of systematic inventory and
research of the caves.
Disturbed Lands: Several old quarry sites need to be inventoried, evaluated
(esp. for exotic plants), and reclaimed. Hazardous materials have been found in
some including buried railroad cars with asbestos and PCBs. Some of these are
40-50 years old. The "Summer Dump" and "South Yard" are two sites that need to
be reclaimed. The State of Oregon as well as the Geologic Resources Division
should be contacted.
Wetlands: Wetlands have been identified but need more detailed study.
Unique Geologic Feature and Interpretation: The caldera left from the explosion
and collapse of Mt. Mazama is one of the most unique features in the world.
Although the last eruption was over 6,000 years ago, the Cascades are still
highly active and the potential for further volcanic activity remains. There is
ample opportunity for interpretation of the past, present and possible future of
Mt. Mazama.
Scoping Meeting Participants
Tim
Connors Geologist NPS, Geologic Resources Division
Sid
Covington Geologist NPS, Geologic Resources Division
Anne Poole Geologist NPS, Geologic Resources Division
Ron
Kerbo Cave Specialist NPS, Geologic Resources Division
Pete Biggam Soil Scientist NPS, Natural Resources Information Div.
Chris Currens Aquatic Biologist USGS, Biological Resources Division
Marsha Davis Geologist NPS, Columbia Cascades Support Office
Charlie Bacon Research Geologist USGS Volcano Hazards Team
Mac
Brock Chief, Resource Management Crater Lake National Park
Mark Buktenica Aquatic Ecologist Crater Lake National Park
Tom
Wiley Geologist Oregon Department of Geology
Daniel Sarr Network Coordinator NPS, Klamath Network
Bob
Truitt Data Manager NPS, Klamath Network
Hanna Waterstat Data Miner NPS, Klamath Network
References
Baldwin, Ewart M., 1976, Geology of Oregon, Rev. Ed., Kendall/Hunt Publishing
Co., Dubuque, Iowa, 147p.
Cranson, K.R., 1982, Crater Lake, Gem of the Cascades: The Geological Story of
Crater Lake National Park (2nd ed.), KRC Press, Lansing, MI, 11p.
Diller, J.S. and Patton, H.B., 1902, The geology and petrography of Crater Lake
National Park: U.S. Geological Survey Professional Paper 3, scale 1:140,800.
Dzurisin, Dan, Stauffer, Peter H., and Hendley, James W. II, 1999, Living with
volcanic risk in the Cascades, U.S. Geological Survey Fact Sheet 165-97 (Rev.
Feb. 1999).
Harris, Ann G., and Tuttle, Esther, 1983, Geology of National Parks (3rd ed.),
Kendall/Hunt Publishing Co., Dubuque, IA, p.242-252.
Harris, Stephen L., 1980, Fire and Ice: The Cascades Volcanoes (Rev. ed.), The
Mountaineers – Pacific Search Press, Seattle, WA, p.84-105.
Kittleman, Lawrence R., 1979, Tephra, in Volcanoes and the Earth’s Interior,
Readings from Scientific American (1982), p.57-67.
MacLeod, N.S. and Sherrod, D.R., 1992, Reconnaissance geologic map of the west
half of the Crescent 1 degree by 2 degrees quadrangle, central Oregon: U.S.
Geological Survey, Miscellaneous Investigations Series Map I-2215, scale
1:250,000.
Moring , Barry, 1983, Reconnaissance surficial geologic map of the Medford 1
degree by 2 degrees quadrangle Oregon-California: U.S. Geological Survey,
Miscellaneous Field Studies Map MF-1528, scale 1:125000.
Page, N.J., Blakeley, R.J., and Cannon, J.K., 1983, Map showing geologic,
geophysical and geochemical characteristics of granitic plutons in the Medford 1
degree by 2 degrees quadrangle, Oregon-California: U.S. Geological Survey,
Miscellaneous Field Studies Map MF-1383-E, scale 1:250,000.
Sherrod, D.R. and Pickthorn, L.B.G., 1992, Geologic map of the west half of the
Klamath Falls 1 degree by 2 degrees quadrangle, south-central Oregon: U.S.
Geological Survey, Miscellaneous Investigations Series Map I-2182, scale
1:250,000.
Smith, J.G., Page, N.J., Johnson, M.G., Moring, B.C., and Gray, Floyd, 1982,
Preliminary geologic map of the Medford 1 degree by 2 degree quadrangle, Oregon
and California, U.S. Geological Survey, Open-File Report OF-82-955, scale
1:250,000.
Wells, F.G., 1955, Preliminary geologic map of southwestern Oregon west of
meridian 122 degrees west and south of parallel 43 degrees north, U.S.
Geological Survey, Mineral Investigations Field Studies Map MF-38, scale
1:250,000.
