Geologic – 02 Introduction

Crater Lake National Park: Geologic Resources Management Issues Scoping Summary




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:

An NCRS soil survey has been completed. The survey was done in 1999-2001. The survey is available on line at 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.

<< previousnext >>