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| Title |
Establishing a Method for Locating Buried Oxbow Lake Deposits Using Electrical Conductivity, Sacramento Valley, California
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| Author(s) |
Ernenwein, Eileen Gloria
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| School/Department |
Department of Geography
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| Institution |
University of Denver
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| Degree Type |
Master's
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| Degree Name |
M.A.
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| Type of Resource |
text
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| Degree Date |
2002 June
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| Digital Origin |
reformatted digital
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| Rights Statement |
All Rights Reserved
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| Reason for Restrictions |
No restrictions
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| Type of Restriction |
No restrictions
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| Keyword(s) |
Geography
Geology
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| Genre |
Dissertations, Academic
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| Abstract |
This study develops a method where electrical conductivity mapping can be used to locate relict oxbow lake sediments, which often have no surface expression. Electrical conductivity mapping was successfully employed to discover six buried oxbow lake deposits, whose presence was confirmed by auger tests. In a meandering river environment, three general types of depositional units are expected: point bars, oxbow lakes, and a number of floodplain depositional facies. Since these three basic depositional units are characterized by distinctly different particle size ranges, they are discernable with geophysical tools that measure the chemical and physical properties of the buried units. To test the ability of EM induction tools to map the location of buried oxbow lake deposits in the middle reach of the Sacramento River Valley, five distinctly different areas were chosen for study. Electrical conductivity maps created with the EM31 device show the bulk conductivity from 1 to 6 meters below the ground. These maps may reveal the location of buried oxbow lake sediments and other associated facies based on the geometry of the conductivity patterns. To evaluate and calibrate these maps, subsurface tests were used to reveal the true nature of the buried sediments. Thus, with only a few carefully placed auger test holes for calibration and a knowledge of the general depositional environments expected in a meandering stream environment, the conductivity maps were used to accurately map the near-surface three-dimensional stratigraphy. In the future studies of this sort can be used as a guide to take intact cores from the buried oxbow lake deposits that have been mapped. If enough are found and numerous cores are taken, dated and analyzed for flood deposits, a flood record could conceivable be constructed going back thousands of years.
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| Handle |
http://hdl.handle.net/10176/codu:55683
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