@misc{indiciae5045b0884582,
  title = {Paleocene-Eocene boundary: Sedimentation in the Potomac River Valley, Virginia and Maryland: field trip guidebook},
  author = {Thomas G. Gibson and Laurel M. Bybell and I. G. C. P. Project 308},
  year = {1991},
  url = {https://pubs.usgs.gov/publication/70221644},
  note = {Source identifier: 70221644}
}