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Reference Source:
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GeoRef, Copyright 2005, American Geological Institute.
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Reference Number:
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1971
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Publication Year:
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2004
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Book Title:
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Geologic map of the Ridgefield Quadrangle, Clark and Cowlitz Counties, Washington.
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Publisher:
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U. S. Geological Survey, United States. Pages: 22, 1 sheet. 2004.
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GeoREF Number:
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2005-022484 (View Original Data File)
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Book Authors:
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Evarts-Russell-C; Dinterman-Philip (compiler); Block-Jessica (compiler)
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Descriptors:
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areal-geology; bedrock-; Clark-County-Washington; Columbia-River-basin; Cowlitz-County-Washington; geologic-maps; landforms-; lithostratigraphy-; maps-; petrology-; Ridgefield-Quadrangle; stratigraphic-units; surficial-geology; tectonic-elements; United-States; USGS-; volcanism-; Washington-
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Source:
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Scientific Investigations Map. 2004.
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Internet Link (URL):
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(Full text) http://pubs.usgs.gov/sim/2004/2844/
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Abstract:
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This map is located just east of the Columbia River about 30 km north of Portland, Oregon. Bedrock, exposed only in the north part of the quadrangle, consists of eroded and tilted Paleogene volcanic rocks unconformably overlain by lava flows of the Miocene Columbia River Basalt Group and by sedimentary deposits that accumulated in the late Neogene Portland Basin. In most areas, the older deposits are covered by either slack-water silt deposited by latest Pleistocene Missoula floods or by Holocene alluvium.
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Document Type:
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Map; Serial; Report
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