Page:Second Geological Survey of Pennsylvania Report of Progress PPP.djvu/6

 {| align="center" width="700px" N.—Levels. O, O².—Catalogue of Specimens.
 * colspan="3" align="center" | Geological Reports of Pennsylvania, 1874—1884.
 * colspan="3" | Second Geological Survey of Pennsylvania Report of Progress PPP map.jpg
 * width="25%" |
 * P.—Coal Flora.
 * width="25%" |
 * P.—Coal Flora.
 * P.—Coal Flora.
 * B, B², M, M², M³.—Chemical Analyses.
 * }