@misc{indiciae20ba78fa8054,
  title = {Geology of the Great Falls Park area, Fairfax County, Virginia},
  author = {P.M. Johnston},
  year = {1956},
  doi = {10.3133/ofr5663},
  url = {https://pubs.usgs.gov/publication/ofr5663},
  note = {Source identifier: ofr5663}
}