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Open-File Report 00-351

Geologic Map and Database of the Salem East and Turner 7.5-Minute Quadrangles, Marion County, Oregon: A Digital Database

By Terry L. Tolan and Marvin H. Beeson

Digital Database by Christopher B. DuRoss

Thumbnail of and link to Salem East 7.5 Quad PDF (4.29 MB)Thumbnail of and link to Turner 7.5 Quad PDF (4.33 MB)Summary

The Salem East and Turner 7.5-minute quadrangles are situated in the center of the Willamette Valley near the western margin of the Columbia River Basalt Group (CRBG) distribution. The terrain within the area is of low to moderate relief, ranging from about 150 to almost 1,100-ft elevation. Mill Creek flows northward from the Stayton basin (Turner quadrangle) to the northern Willamette Valley (Salem East quadrangle) through a low that dissects the Columbia River basalt that forms the Salem Hills on the west and the Waldo Hills to the east. Approximately eight flows of CRBG form a thickness of up to 700� in these two quadrangles. The Ginkgo intracanyon flow that extends from east to west through the south half of the Turner quadrangle is exposed in the hills along the southeast part of the quadrangle.

Previous geologic mapping by Thayer (1939) and Bela (1981) while providing the general geologic framework did not subdivide the CRBG which limited their ability to delineate structural elements. Reconnaissance mapping of the CRBG units in the Willamette Valley indicated that these stratigraphic units could serve as a series of unique reference horizons for identifying post-Miocene folding and faulting (Beeson and others, 1985,1989; Beeson and Tolan, 1990). Crenna, et al. (1994) compiled previous mapping in the Willamette Valley in a study of the tectonics of the Salem area.

The major emphasis of this study was to identify and map CRBG units within the Salem East and Turner Quadrangles and to utilize this detailed CRBG stratigraphy to identify and characterize structural features. Water well logs were used to provide better subsurface stratigraphic control. Three other quadrangles (Scotts Mills, Silverton, and Stayton NE) in the Willamette Valley have been mapped in this way (Tolan and Beeson, 1999).

This area was a lowland area of weathered and eroded marine sedimentary when the Columbia River basalts encroached on this area approximately 15-16 m.y. ago. An incipient Coast Range apparently stopped or diverted the fluid lava flows from moving much farther westward toward the coast at this latitude. It is assumed also that an ancestral Willamette River flowed northward through this low-lying area so that water was present as streams and ponds along the flood plain.

First posted January 3, 2001

Maps are 30 x 35 inches. Scale 1:24,000.

  • Maps TAR.Z (25.6 MB)
    A tarred and gzipped package that contains both maps as Postscript files. Will open into a directory named "00351ps" when unzipped and untarred.
  • Database TAR.Z (29.2 MB)
    The complete database package as a tarred, gzipped file. Will open into a directory named "00351db" when unzipped and untarred.
  • Database ZIP (29.2 MB)
    The same data as above but in zip form. Will open into a directory named "00351db" when unzipped.

For additional information, contact:
National Cooperative Geologic Mapping Program
U.S. Geological Survey
12201 Sunrise Valley Drive, MS 908
Reston, VA 20192

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Suggested citation:

Tolan, Terry L. and Beeson, Marvin H.; Digital Database By DuRoss, Christopher B., 2001, Geologic Map and Database of the Salem East and Turner 7.5-Minute Quadrangles, Marion County, Oregon: A Digital Database: U.S. Geological Survey Open-file Report 00-351, https://pubs.usgs.gov/of/2000/0351/.




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