@misc{indiciae1d6ed38a9c1e,
  title = {Preliminary map showing Quaternary deposits and their dating potential in the conterminous United States},
  author = {S. M. Colman and K. L. Pierce},
  year = {1979},
  doi = {10.3133/mf1052},
  url = {https://pubs.usgs.gov/publication/mf1052},
  note = {Source identifier: mf1052}
}