Preliminary quaternary geologic maps of Santa Clara Valley, Santa Clara, Alameda, and San Mateo counties, California: A digital database

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Description This digital map database, which is compiled from previously unpublished and open-filed U.S. Geol. Survey reports (Wesling and Helley, 1989), represents the general distribution and identity of Quaternary deposits in eight 7.5 minute quadrangles in the
Originators Helley, E. J.; Graymer, Russell W.; Phelps, Geoffrey A.; Showalter, Patrick; and Wentworth, Carl M.
Publication U.S. Geological Survey Open-File Report 94-231

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States or counties


Principal facts for gravity stations, Appendix A of the report

Label Definition
STA Gravity station identification
LATITUDE Geographic latitude
LONGITUDE Geographic longitude
ELEV_UNITS Units of elevation
ELEVATION Elevation of surface at the site
OBS_GRAV Observed gravity
FR_AIR_AN Free air anomaly
BOUG_SIMP Simple Bouguer anomaly
BOUG_COMPL Complete Bouguer anomaly
IZT_CORR Inner terrain correction
TOT_CORR Total terrain correction
UNCER_CBGA Uncertainty in the complete Bouguer anomaly


Handheld magnetometer measurements, Appendix B of the report

Label Definition
STATION Unique identifier for the measurement station
EASTING_M East-west coordinate in UTM zone 12N, NAD27
NORTHING_M North-south coordinate in UTM zone 12N, NAD27
AVE_NT Reading average
CORR_SRA01 Reading corrected for diurnal variation to base station sra-01
IGRF_NT IGRF reference field value
CORR_IGRF Anomaly calculated with respect to IGRF value
COMMENTS Additional information about the station