Final EIS Appendix 22 

APPENDIX 22—PROBABLE FOSSIL YIELD 

CLASSIFICATION 

Table A22-1. Probable Fossil Yield Classification by Formation 

(State of Wyoming) 

Formation Age Class1 Geologic Map2

Adaville Formation Upper Cretaceous 3 Kav 

Alcova Limestone Middle Triassic 3 TRc, TRPcg, TRPjs, MzPz 

Almond Formation Upper Cretaceous 3 Kal, Kmv 

Amsden Formation Pennsylvanian to Upper 

Mississippian 3 PIPMa, PIPM, PM, MzPz 

Ankareh Formation Upper and Lower Triassic 3 JTRnd, Trad 

Aspen Shale or Formation Lower Cretaceous 3 Ka 

Arikaree Group or Formation Miocene and Oligocene 5 Tmo 

Aycross Formation Middle Eocene 5 Ta 

Bacon Ridge Sandstone Upper Cretaceous 3 Kb, Ksb 

Battle Spring Formation Eocene to Upper 

Paleocene 3 Tbs 

Baxter Shale Upper Cretaceous 3 Kba 

Bearpaw Formation Upper Cretaceous 3 Kfb, Klm 

Bear River Formation Lower Cretaceous 3 Kbr 

Belle Fourche Shale Upper Cretaceous 3 Kgb, Kgbm 

Bighorn Dolomite Upper Ordovician 2 Ob, DO, OC, MDO, MO, 

Pzr 

Bishop Conglomerate Oligocene 3 Tbi 

Blair Formation Upper Cretaceous 3 Kbl 

Blind Bull Formation Upper Cretaceous 3 Kbb 

Bridger Formation Middle Eocene 5 Tb 

Browns Park Formation Late to Middle Miocene 2 Tm 

Brule Formation Oligocene 5 Twrb, Twr 

Bug Formation Pleistocene to Pliocene 2 QTb 

Caldwell Canyon Volcanics Pliocene and Miocene 2 Tcv 

Cambrian Units Cambrian 2 Cr, Pzr 

Camp Davis Formation Middle Miocene 2 Tcd 

Carlile Shale Upper Cretaceous 3 Kcl, Knc 

Casper Formation Permian to Pennsylvanian 3 PIPc, PIPcf, PIPM, MzPz 

Chadron Formation Oligocene and Eocene 5 Twrc, Twr 

Chugwater Group or Formation Triassic 3 JTRnd, JTRgc, TRc, TRcd, 

TRPcg, TRPjs, MzPz 

Cloverly Formation Lower Cretaceous 5 KJ, KJs, KJg, KTR, MzPz 

Coalmont Formation Eocene and Paleocene 3 Tco 

Pinedale RMP A22-1 
Appendix 22 Final EIS 

A22-2 Pinedale RMP 

Formation Age Class1 Geologic Map2

Cody Shale Upper Cretaceous 3 Kc, Kcf 

Cokeville Formation Lower Cretaceous 3 Kss 

Colter Formation Lower Miocene 2 Tc 

Conant Creek Tuff Upper Miocene 2 Tcc 

Crandall Conglomerate Lower Eocene 3 Tcr 

Crooks Gap Conglomerate Middle Eocene 3 Tcg 

Crow Mountain Sandstone Upper Triassic 3 TRc, TRPcg, TRPjs, MzPz 

Darby Formation Mississippian to Devonian 2 MD, MDO, Pzr 

Deadwood Formation Ordovician to Cambrian 2 OC, Pzr 

Devils Basin Formation Upper Paleocene 3 Tdb 

Dinwoody Formation Lower Triassic 3 JTRnd, TRad, TRcd, 

TRPcg, MzPz 

Eagle Sandstone Upper Cretaceous 3 Ket 

Ellis Group Upper to Middle Jurassic 3 KJk 

Englewood Limestone Lower Mississippian to 

Lower Devonian 3 MDe, Pzr 

Ericson Sandstone Upper Cretaceous 3 Ke 

Evanston Formation Paleocene to Upper 

Cretaceous 3 TKe 

Everts Formation Upper Cretaceous 3 Ket 

Fall River Formation Lower Cretaceous 3 KJ 

Ferris Formation Paleocene to Upper 

Cretaceous 5 TKf 

Flathead Sandstone Middle Cambrian 2 OC, Cr, Pzr 

Forelle Limestone Permian 2 TRPjs, Pfs 

Fort Union Formation Paleocene 3 Tfu, Tft, Tflt, Tfl, Tftl, Tftr 

Fountain Formation Upper to Middle 

Pennsylvanian 2 PIPcf 

Fowkes Formation Pliocene(?) and Eocene 3 Tf 

Fox Hills Formation Upper Cretaceous 3 Kfh, Kfl, Kfb, Klm 

Frontier Formation Upper Cretaceous 3 Kf, Kft, Kcf, Knt 

Gallatin Group or Limestone Upper Cambrian 2 OC, Cr, Pzr 

Gannett Group Lower Cretaceous 3 Kg 

Glacial deposits Holocene and Pleistocene 1 Qg 

Goose Egg Formation Lower Triassic to Permian 2 TRPg, TRPcg, MzPz 

Greenhorn Formation Upper Cretaceous 3 Kgb, Kgbm 

Green River Formation Middle to Lower Eocene 5 Tgl, Tglu, Tgrw, Tgt, Tgw, 

Tgwt, Twg 

Gros Ventre Formation Upper and Middle 

Cambrian 2 OC, Cr, Pzr 

Guernsey Formation Upper Devonian 2 MDg 
Final EIS Appendix 22 

Pinedale RMP A22-3 

Formation Age Class1 Geologic Map2

Gypsum Spring Formation Middle Jurassic 3 

KJg, KTR, Jsg, Jst, JTR, 

JTRgn, JTRnd, JTRgc, 

MzPz 

Hanna Formation Upper Paleocene 5 Tha 

Harebell Formation Upper Cretaceous 3 Kha 

Hartville Formation Permian to Mississippian(?) 3 PIPh 

Heart Lake Conglomerate Pliocene 2 Thl 

Hilliard Shale Upper Cretaceous 3 Kh 

Hoback Formation Paleocene 5 Th 

Hominy Peak Formation Upper Eocene 3 Thp 

Ice Point Conglomerate Upper Eocene 3 Tip 

Indian Meadows Formation Lower Eocene 5 Tim, Twim 

Inyan Kara Group Lower Cretaceous 3 KJ 

Jefferson Formation Upper Devonian 2 MD, DO, MDO 

Jelm Formation Upper Triassic 3 TRc, TRPjs 

Kootenai Formation Upper Cretaceous 3 KJk 

Laketown Dolomite Upper and Middle Silurian 2 Sl 

Lakota Formation Lower Cretaceous 3 KJ 

Lance Formation Upper Cretaceous 5 Kl, Klm 

Landslide Creek Formation Upper Cretaceous 5 Klc 

Langford Formation Eocene 2 Ttl, Tts 

Lebo Member Middle Paleocene 3 Tfl, Tftl, Tflt 

Lewis Shale Upper Cretaceous 3 Kle, Kfl, Klm, Kml 

Lodgepole Formation Lower Mississippian 3 PIPM, Mm, MD, MDO, MO, 

Pzr 

Madison Limestone Mississippian Through 

Upper Devonian 3 Mm, PIPM, MD, MDO, MO, 

Pzr 

Meagher Limestone Middle Cambrian 2 OC 

Medicine Bow Formation Upper Cretaceous 3 Kmb 

Meeteetse Formation Upper Cretaceous 3 Km, Klm, Kml 

Mesaverde Group or Formation Upper Cretaceous 3 Kmv, Kal, Ke, Kr, Kbl 

Minnekahta Limestone Permian 3 Pm, Pmo, Pzr 

Minnelusa Formation Pennsylvanian 2 PIPm, Pzr 

Mission Canyon Formation Mississippian 3 PIPM, Mm, MD, MDO, MO, 

Pzr 

Moonstone Formation Upper Miocene 3 Tmu 

Morrison Formation Upper Jurassic 5 KJk, KJ, KJs, KJg, KTR, 

MzPz 

Mowry Shale Lower Cretaceous 3 Kmr, Kmt, Knt, Kgbm, Kft 

Newcastle Sandstone Lower Cretaceous 3 Kns 

Niobrara Formation Upper Cretaceous 5 Kn, Ksn, Knt, Knc 

North Park Formation Upper Miocene 3 Tmu 
Appendix 22 Final EIS 

A22-4 Pinedale RMP 

Formation Age Class1 Geologic Map2

Norwood Tuff Pliocene and Eocene 3 Tf 

Nugget Sandstone Jurassic and Triassic 3 JTRn, JTRnd, KTR, JTR, 

JTRgn, JTRgc, MzPz 

Ogallala Group or Formation Pliocene to Miocene 5 Tmu 

Opeche Shale Permian 2 Pmo, Pzr 

Pahasapa Limestone Mississippian 2 Pzr, MDe 

Park Shale Middle Cambrian 2 OC 

Pass Peak Formation Lower Eocene 3 Tp 

Phosphoria Formation Permian 3 Pp, PIPMa, MzPz 

Pierre Shale Upper Cretaceous 3 Kp 

Pinyon Conglomerate Paleocene to Upper 

Cretaceous 3 TKp 

Popo Agie Member Upper Triassic 3 TRc, TRPcg, TRPjs, MzPz 

Preuss Formation or Sandstone Upper to Middle Jurassic 3 Jst 

Quadrant Formation Pennsylvanian 2 PIPMa 

Quealy Formation Lower Cretaceous 3 Kss 

Red Peak Member Lower Triassic 2 TRc, TRPcg, TRPjs, MzPz 

Rierdon Formation Upper Jurassic 3 KJk 

Rock Springs Formation Upper Cretaceous 3 Kr 

Sage Junction Formation Lower Cretaceous 3 Kss 

Salt Lake Formation Pliocene and Miocene 3 Tsl 

Satanka Shale Permian 2 TRPjs, Pfs 

Sawtooth Formation Upper Jurassic 3 KJk 

Shooting Iron Formation Pliocene 2 Tsi 

Skull Creek Shale Lower Cretaceous 3 Kns 

Smiths Formation Lower Cretaceous 3 Kss, Kws 

Sohare Formation Upper Cretaceous 3 Kso, Ksb 

South Pass Formation Upper Miocene 3 Tmu 

Spearfish Formation Upper Triassic to Upper 

Permian 2 TRPs 

Split Rock Formation Middle to Early Miocene 3 

Steele Shale Upper Cretaceous 3 Ks, Ksn 

Stump Formation Upper to Middle Jurassic 3 Jst 

Sundance Formation Upper Jurassic 5 Js, KJs, KJg, KTR, Jsg, 

JTR, MzPz 

Sunlight Group Upper Eocene 1 Ts, Tts 

Swift Formation Upper Jurassic 3 KJk 

Tatman Formation Lower Eocene 5 Tta 

Teewinot Formation Upper Miocene 3 Tte 

Telegraph Creek Formation Upper Cretaceous 3 Ket 

Tensleep Sandstone Permian to Pennsylvanian 2 PIPMa, PM, MzPz 
Final EIS Appendix 22 

Pinedale RMP A22-5 

Formation Age Class1 Geologic Map2

Tepee Trail Formation Upper Eocene 5 Tt 

Tertiary, Undiff Pliocene to Oligocene 3 Tu 

Thaynes Limestone Lower Triassic 3 JTRnd, TRad 

Thermopolis Shale Lower Cretaceous 3 Kmt, Kft, Knt 

Thomas Fork Formation Lower Cretaceous 3 Kss 

Three Forks Formation Upper Devonian 2 MD, DO, MDO 

Tongue River Member Upper Paleocene 3 Tftr, Tftl 

Tullock Member Lower Paleocene 3 Tft, Tflt 

Twin Creek Limestone Upper to Middle Jurassic 3 Jst 

Two Ocean Formation Eocene 2 Ttl, Tts 

Wagon Bed Formation Middle Eocene 5 Twb 

Wapiti Formation Upper Eocene 1 Twp, Tts, Ts 

Wasatch Formation Lower Eocene 5 

Tw, Tgc, Tgrw, Twc, Twd, 

Twg, Twk, Twlc, Twm, 

Twmo, Twn 

Washakie Formation Upper Eocene 5 Twa 

Washburn Group Middle Eocene 1 Taw 

Wayan Formation Lower Cretaceous 3 Kws 

Wells Formation Permian to Pennsylvania 3 PIPMa, PIPM 

White River Group Oligocene and Eocene 5 Twr, Twrb, Twrc, Twru, 

Tmo 

Whitewood Dolomite Upper Ordovician 2 OC, Pzr 

Wiggins Formation Upper Eocene 5 Twi 

Willwood Formation Lower Eocene 5 Twl 

Wind River Formation Lower Eocene 5 Twdr, Twim 

Winnipeg Formation Middle Ordovician 2 OC, Pzr 

Wolsey Shale Middle Cambrian 2 OC 

Woodside Formation or Shale Lower Triassic 3 JTRnd, TRad 

1

Class ranking from Northern Great Plains Probable Fossil Yield Classification report, by Ross Secord, Univ. of Wyoming, 1996; 

Fossil Vertebrate Localities of Southwestern Wyoming: A literature search, locality record, and formation evaluation by Peter 

Robinson, David Daitch, and Jennifer Haessig, Univ. of Colorado Museum, BLM contract KAA 000002, 2002; and professional 

judgment by Dale Hanson, Regional Paleontologist, Wyoming State Office, BLM 2002.

2

Because the geologic map uses special characters not available in standard font sets, the following existing characters that 

seemed close to geologic symbols were used (D. Hanson, 2002): TR = Triassic Period; IP = Pennsylvanian Period; C = 

Cambrian Period; @ = Proterozoic and late Archean times. All other symbols are the same as those commonly used in geologic 

mapping. 

Source: Geologic Map of Wyoming. Compiled by Love and Christiansen, 1985