@misc{indiciaedc4db477785f,
  title = {Preliminary geologic map of the Walnut Creek Quadrangle, Contra Costa County, California},
  author = {T. W. Dibblee},
  year = {1980},
  doi = {10.3133/ofr80351},
  url = {https://pubs.usgs.gov/publication/ofr80351},
  note = {Source identifier: ofr80351}
}