@misc{indiciaedfaa48f65d78,
  title = {Preliminary geologic map emphasizing bedrock formations in Contra Costa County, California: A digital database},
  author = {R. W. Graymer and David Lawrence Jones and Earl E. Brabb},
  year = {1994},
  doi = {10.3133/ofr94622},
  url = {https://pubs.usgs.gov/publication/ofr94622},
  note = {Source identifier: ofr94622}
}