@misc{indiciaee39edd734cd6,
  title = {Preliminary geologic map of the Las Trampas Ridge Quadrangle, Contra Costa and Alameda counties, California},
  author = {T. W. Dibblee},
  year = {1980},
  doi = {10.3133/ofr80545},
  url = {https://pubs.usgs.gov/publication/ofr80545},
  note = {Source identifier: ofr80545}
}