@misc{indiciaed2caac0db80c,
  title = {Use of altered volcanic ash falls in stratigraphic studies of coal-bearing sequences: an example from the Upper Cretaceous Ferron Sandstone Member of the Mancos Shale in central Utah.},
  author = {Thomas A. Ryer and R.E. Phillips and B.F. Bohor and R. M. Pollastro},
  year = {1980},
  doi = {10.1130/0016-7606(1980)91<579:uoavaf>2.0.co;2},
  url = {https://pubs.usgs.gov/publication/70012353},
  note = {Source identifier: 70012353}
}