@misc{indiciaefc5aef53e820,
  title = {Early Proterozoic volcanogenic sequences in central Colorado: Colorado Scientific Society fall field trip, September 6-8, 1991},
  author = {John Calvin Reed and Kenneth Lee Shropshire},
  year = {1991},
  doi = {10.3133/ofr91431},
  url = {https://pubs.usgs.gov/publication/ofr91431},
  note = {Source identifier: ofr91431}
}