@misc{indiciae88aec69ac7f0,
  title = {Contour map of the base of saprolite, Vienna Quadrangle, Virginia-Maryland},
  author = {Sherman K. Neuschel and A.J. Froelich},
  year = {1975},
  doi = {10.3133/ofr75519},
  url = {https://pubs.usgs.gov/publication/ofr75519},
  note = {Source identifier: ofr75519}
}