Digital geologic map and map database of parts of Marin, San Francisco, Alameda, Contra Costa, and Sonoma Counties, California

Metadata Updated: December 11, 2019

This digital map database, compiled from previously published and unpublished data, and new mapping by the authors, represents the general distribution of bedrock and surficial deposits in the mapped area. Together with the accompanying text file (mageo.txt, mageo.pdf, or, it provides current information on the geologic structure and stratigraphy of the area covered. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:62,500 or smaller.

Access & Use Information

License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

Downloads & Resources


Metadata Date June 13, 2016
Metadata Created Date October 10, 2019
Metadata Updated Date December 11, 2019
Reference Date(s) January 1, 1999 (publication)
Frequency Of Update asNeeded
Frequency Of Update asNeeded

Metadata Source

Harvested from DOI CKAN Harvest Source

Graphic Preview

Image of entire map

Additional Metadata

Resource Type Dataset
Metadata Date June 13, 2016
Metadata Created Date October 10, 2019
Metadata Updated Date December 11, 2019
Reference Date(s) January 1, 1999 (publication)
Responsible Party USGS Western Geologic Mapping Team (Point of Contact)
Contact Email
Access Constraints Use Constraints: Uses of this digital geologic map should not violate the spatial resolution of the data. Although the digital form of the data removes the constraint imposed by the scale of a paper map, the detail and accuracy inherent in map scale are also present in the digital data. The fact that this database was edited for a scale of 1:62,500 means that higher resolution information is not present in the dataset. Plotting at scales larger than 1:62,500 will not yield greater real detail, although it may reveal fine-scale irregularities below the intended resolution of the database. Similarly, where this database is used in combination with other data of higher resolution, the resolution of the combined output will be limited by the lower resolution of these data., Access Constraints: None
Bbox East Long -122.24855051
Bbox North Lat 38.2626288
Bbox South Lat 37.73826442
Bbox West Long -122.9902372
Coupled Resource
Frequency Of Update asNeeded
Graphic Preview Description Image of entire map
Graphic Preview File
Graphic Preview Type JPEG
Harvest Object Id 2c6cb016-c921-47a4-a910-565de45643c4
Harvest Source Id 34ce571b-cb98-4e0b-979f-30f9ecc452c5
Harvest Source Title DOI CKAN Harvest Source
Licence Mention of commercial products or organizations is descriptive and does not constitute an endorsement by the government of those products or organizations.
Metadata Language
Metadata Type geospatial
Spatial Data Service Type
Spatial Reference System
Spatial Harvester true

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