@misc{indiciae6b6d36b7aad5,
  title = {Preliminary Quaternary geologic maps of Santa Clara Valley, Santa Clara, Alameda, and San Mateo counties, California: A digital database},
  author = {Edward J. Helley and R. W. Graymer and G. A. Phelps and P. K. Showalter and C. M. Wentworth},
  year = {1994},
  doi = {10.3133/ofr94231},
  url = {https://pubs.usgs.gov/publication/ofr94231},
  note = {Source identifier: ofr94231}
}