U.S. Geological Survey
Open-File Report 00-043
Version 2.0

Bathymetric, geophysical, and geologic sample data from Medicine Lake, Siskiyou County, northern California

By Jonathan R. Childs¹, Jacob B. Lowenstern², R. Lawrence Phillips¹, Patrick Hart¹, James J. Rytuba³, John A. Barron², Scott W. Starratt², and Sarah Spaulding⁴

2000

(1) Mail Stop 999, 345 Middlefield Road, Menlo Park, CA 94025 USA
(2) Mail Stop 910, 345 Middlefield Road, Menlo Park, CA 94025 USA
(3) Mail Stop 901, 345 Middlefield Road, Menlo Park, CA 94025 USA
(4) California Academy of Sciences, Dept. of IZ&G, Golden Gate Park, San Francisco, CA 94118 USA

Photograph of Medicine Lake with Mt. Shasta in background.
Aerial view of Medicine Lake taken looking southwest towards Mt. Shasta. USGS photograph by Julie Donnelly-Nolan.

Contents:: A. Introduction
B. Bathymetric and geophysical program
C. Sediment Coring program
D. Mercury analysis
E. Paleontologic analysis; F. List of Tables; G. List of Figures
I. Acknowledgements

Appendices:
I. Bathymetric and geophysical program field notes (observer logs)
II. Summary of seismic reflection profile lines
III. ASCII bathymetric data file

Figure A1: Location of Medicine Lake Volcano, California.

Further information about Medicine Lake (as of September 1999):
Perimeter of Lake: 6213 m or 20,380 ft
Area of Lake: 1.65 square km (408 acres)
Volume of lake: 13,400,000 cubic meters (3.5 billion gallons; 10,860 acre-feet)
Elevation of lake surface: 2036m (6680 feet)
Greatest depth: 46.4 m (152.2 feet)
Mean depth: 7.3m (23.9) feet
Median depth: 4.9m (16.1 feet)

Introduction

In September, 1999, the U.S. Geological Survey acquired high-resolution bathymetry, seismic reflection profiles, and geologic sample data from Medicine Lake, a high altitude (2,036 m) lake located within the summit caldera/basin at Medicine Lake Volcano (MLV), a dormant Quaternary shield volcano located in the Cascade Range, 50 km northeast of Mt. Shasta. It last erupted less than 1000 years ago. The purpose of this work was to assess whether sediments in the lake might provide a high-resolution record of the climate, volcanic and geochemical (particularly mercury) history of the region. We are still working with our data to assess whether the sediments are appropriate for further study. This report provides a summary of what we have learned to date.

Selected data products include:

A bathymetric map of the lake (in meters).
Another map with depth in feet.
Forty high-resolution seismic reflection profiles of the lake, including seventeen acquired along east-west tracks, and twenty-three acquired along northeast-southwest tracks (see map showing track lines).
A temperature profile of the lake at its deepest point.
A perspective-view of the lake bathymetry.
Descriptions of nine sediment cores, ranging in depth from 10 to 100 cm, from various locations within the lake and surrounding area.
Map of sampling/coring locations.
Mercury analyses of lake water and sediment samples from the lake bottom.
Description of diatoms and other microfossils found in lake water and sediments.
Data for Downloading

Tables include:

Table 1.Information on core locations and characteristics.
Table 2. Mercury and methyl mercury concentration in sediment from cores at Medicine Lake.
Table 3. Analyses of mercury and methyl mercury in sediment samples from core number 6.
Table 4. Analysis of mercury and methyl mercury in water from Medicine Lake.
Appendix 2. Summary of seismic-reflection profile lines.
Appendix 3. Bathymetric Data File in ASCII format.

Figures include:

Figure A1 Location map of Medicine Lake Volcano.
Figure A2. Photo of Medicine Lake from the northeast.
Figure A3. Perspective view of the Medicine Lake highland and surrounding region.
Figure A4. Perspective view of geology and topography around Medicine Lake.
Figure B1: The Geopulse and Seistec sources towed behind boat.
Figure B2: The Fast Eddy (a Boston Whaler).
Figure B3: Map 1: Bathymetric map of Medicine Lake contoured at 5-m intervals. Click here to download this file as an Adobe Illustrator 8 document (128 kb).
Figure B4: Map 2: Bathymetric map of Medicine Lake contoured at 10-foot intervals. Click here to download this file as an Adobe Illustrator 8 document (152 kb).
Figure B5: A 3-D perspective view of the lake bathymetry as seen from the SW.
Figure B6: Map 3: Track lines showing locations of seismic profiles.
Figure B7: Representative seismic line (N-STrackline 210) near deep hole in lake.
Figure B8: Highlight of Trackline 210.
Figure B9: Profile of temperature with depth in Medicine Lake.
Figure C1: Stratigraphy summary.
Figure C2 Key to sedimentary structures.
Figure C3: Map of sediment core sample locations.
Figure C4: Photograph of hammer core #3.
Figure C5: Photograph of box core #6.
Figures C7 (1-18): Stratigraphy and texture diagrams for cores 1-9.
Figure E1: Photograph of the planktonic diatom Cyclotella.
Figure E2: Photograph of benthonic diatom Navicula.
Figure E3: Photographs of other planktonic diatoms.
Figure E4: Photographs of other benthonic diatoms.
Figure E5: Photographs of Chrysophyte stomatocysts.

Geographic location, geologic setting, and physiographic environment of the Medicine Lake volcanic region are described at:

http://vulcan.wr.usgs.gov/Volcanoes/MedicineLake/framework.html

http://vulcan.wr.usgs.gov/Volcanoes/California/Maps/map_medlake_shasta.html

http://vulcan.wr.usgs.gov/Volcanoes/MedicineLake/Maps/map_lavabeds.html

For questions about the scientific content of this report, please contact Jon Childs or Jake Lowenstern

Acknowledgements

We appreciate considerable logistical assistance from Jayne Biggerstaff, Dan Meza, Brad Reed, and Randall Sharp of the U.S. Forest Service, Modoc National Forest. At the USGS, Julie Donnelly-Nolan and Duane Champion offered advice and geologic expertise. Gerald O'Brien and Larry Kooker kept the Fast Eddy and the geophysical surveying equipment in top working order and the field program running smoothly. This work was funded through the USGS Volcano Hazards, Mineral Resources, Earth Surface Dynamics and Coastal and Marine Surveys Programs as well as though a grant from the Office of the Chief Geologist.

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This report is available via print on demand.

This report is also available in printed format from:

USGS Information Services
Box 25286 Federal Center
Denver, CO 80225
Telephone: 1-888-ASK-USGS
E-mail: infoservices@usgs.gov

The URL for this page is: http://pubs.usgs.gov/of/2000/of00-043
Please send comments and suggestions, or report problems, to: Michael Diggles
Created March 6, 2000 (cad)
Updated: October 15, 2007 (bwr)