Determination of bench-mark elevations at Bethel Island and vicinity, Contra Costa and San Joaquin counties, California, 1987
Open-File Report
88-498
By: J. C. Blodgett, M. E. Ikehara, and William F. McCaffrey
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Abstract
Elevations of 49 bench marks in the southwestern part of the Sacramento-San Joaquin River Delta were determined during October and November 1987. A total of 58 miles of level lines were run in the vicinity of Bethel Island and the community of Discovery Bay. The datum of these surveys is based on a National Geodetic Survey bench mark T934 situated on bedrock 10.5 mi east of Mount Diablo and near Marsh Creek Reservoir. The accuracy of these levels, based on National Geodetic Survey standards, was of first, second, and third order, depending on the various segments surveyed. Several bench marks were noted as possibly being stable, but most show evidence of instability. (USGS)
Suggested Citation
Blodgett, J.C., Ikehara, M.E., McCaffrey, W.F., 1988, Determination of bench-mark elevations at Bethel Island and vicinity, Contra Costa and San Joaquin counties, California, 1987: U.S. Geological Survey Open-File Report 88-498, iv, 11 p. :maps ;28 cm., https://doi.org/10.3133/ofr88498.
ISSN: 2331-1258 (online)
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | Determination of bench-mark elevations at Bethel Island and vicinity, Contra Costa and San Joaquin counties, California, 1987 |
| Series title | Open-File Report |
| Series number | 88-498 |
| DOI | 10.3133/ofr88498 |
| Year Published | 1988 |
| Language | ENGLISH |
| Publisher | U.S. Geological Survey, |
| Description | iv, 11 p. :maps ;28 cm. |