@misc{indiciae90c5e012b503,
  title = {Preliminary geologic and tectonic maps of Oregon east of the 121st meridian},
  author = {G. W. Walker},
  year = {1973},
  doi = {10.3133/mf495},
  url = {https://pubs.usgs.gov/publication/mf495},
  note = {Source identifier: mf495}
}