@misc{indiciaeff92d0fdbdf0,
  title = {Geologic Map of Loudoun County, Virginia},
  author = {Scott Southworth and William C. Burton and J. Stephen Schindler and Albert J. Froelich},
  year = {2006},
  doi = {10.3133/i2553},
  url = {https://pubs.usgs.gov/publication/i2553},
  note = {Source identifier: i2553}
}