The cyclothem system of detailed stratigraphic classification as applied to the Pennsylvanian System in Illinois
Paper presented at GSA meeting, December 1946. Revised version included, February 1947, 18 pages.
Manuscripts, maps, fieldnotes, and photographs may be viewed in-house only. Please contact the ISGS Special Collections Curator, Anne Huber, for an appointment at 217-300-0005 or email firstname.lastname@example.org Monday thru Friday, 8am-noon or 1pm-5pm.