@misc{indiciae1630027010ad,
  title = {Sedimentary formations of Washington, D.C., and vicinity},
  author = {N. H. Darton},
  year = {1947},
  doi = {10.3133/70211262},
  url = {https://pubs.usgs.gov/publication/70211262},
  note = {Source identifier: 70211262}
}