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Home , Carlile Shale, Cody Shale, Evanston Formation, Ferris Formation, Frontier Formation, Lewis Shale

STATE GEOLOGICAL SURVEY Open File Report 2017-3 Thomas A. Drean CORRELATION OF THE UPPER STRATA OF WYOMING Stratigraphic Chart Director and State Geologist Upper Cretaceous Laramie, Wyoming by Ranie M. Lynds and Joshua S. Slattery Wyoming Interpreting the past, providing for the future 2017

Western Hanna Laramie Bighorn Denver Greater Green Basin Wyoming Basin Basin Basin Basin A B C D E F G H I J K L M N O P Q R S T U V W X Y

Age Period Epoch Stage and Stage Polarity U.S. Western Interior U.S. Western Interior U.S. Western Interior North American U.S. Western Interior Southern Jackson Northwestern Southern Eastern Eastern Atlantic Rocky Point Separation Lost Soldier Tully Rawlins Hanna Laramie Western Southern and Eastern Bighorn Northwestern Salt Creek Southwestern Southeastern Central Northwestern Denver (Ma) Boundary Chron Radiometric Ammonite Inoceramid Land Palynostratigraphic Thrust Belt Hole and Rock Springs Rock Springs Rock Springs Washakie Rim Rim Ranch Draw Basin Basin, Wind River Central Wind Wind River Basin Powder Powder Powder River Black Hills Basin (Ma) Age (Ma) Biozone Biozone Age Biozone Hoback Basin Uplift Uplift Uplift Basin Rock River Basin River Basin Basin River Basin River Basin Basin

(7, 56, 77) (7, 56, 74) (8, 49, 54, 55, 56, 69, 72) (7, 23, 25, 56, 74) (7, 56, 74) (2, 33, 35, 77) (50) (6, 10, 29, 30, 47, 53, (6, 11, 12, 22, 32, 37, (12, 26, 30, 64, 72, (12, 26, 30, 36, 63, 64, (12, 19, 20, 26, 29, 30, (1, 12, 21, 30, 36, 58, (1, 12, 30, 36, 39, 58, (1, 12, 30, 36, 58, 74) (1, 12, 30, 36, 58, 64, (6, 12, 30, 36, 41, 58, (1, 12, 30, 36, 58, 74) (1, 12, 30, 36, 58, 74) (5, 12, 15, 17, 20, 57, (6, 12, 19, 20, 46, 74, (12, 13, 59, 74) (12, 13, 59, 74) (9, 12, 13, 14, 19, 59, (12, 17, 24, 28, 40, 43, (12, 40, 52, 59, 74) (3, 12, 17, 51, 59, 74) (12, 40, 52, 59, 68, 74) (12, 16, 17, 18, 40, 44, (4, 12, 52, 59, 61, 74) (4, 12, 42, 46, 52, 59, (12, 27, 31, 48, 70, 73, 65, 66, 67, 72, 75, 76) 47, 67, 74) 74) 72, 74) 36, 62, 63, 67, 74) 64, 74) 74) 74) 59, 60, 74) 74, 78) 78) 74) 52, 59, 74) 45, 46, 52, 59, 74) 61, 74) 74)

Lebo Lebo Lebo Lebo Lebo Torrejonian main body upper C28n P3 (part) China China China China China China China China China Member Member Member Member Member Fort Union (part) lower lower lower (part) (part) (part) (part) (part) Formation Butte Butte Butte Butte Butte Butte Butte Butte Butte Member Member Member Member Member Member Member member member member Fort Union Fort Union No Record (part) Member Member No Record (part) (part) (part) (part) (part) (part) (part) (part) (part) (part) (part) Formation Formation (part) (part) (part) (part)

(part) (part) C28r

aleocene aleogene P2 65 middle P P Puercan Tullock Tullock Tullock Tullock Tullock Fort Union Formation Fort Union Formation Fort Union Formation Fort Union Formation Fort Union Formation Fort Union Formation Fort Union Formation Fort Union Formation Fort Union Formation Fort Union Formation C29n Fort Union Formation Member Member Member Member Member Fort Union Formation Fort Union Formation Fort Union Formation Fort Union Formation Fort Union Formation P1 Pinyon Conglomerate 66.0 ± 0.5 C29r 66.02 ± 0.08 Red Rim Red Rim Red Rim Red Rim Red Rim Red Rim Red Rim lower Unzoned Member Member Member Member Member (?) Member (?) Member (?) C30n Torrington Wodehouseia spinata Lance Lance Formation Member Hoploscaphites Assemblage Biozone Lance upper Unzoned Lancian Formation Formation Lance Lance Lance nebrascensis Medicine Bow Lance Formation Formation Formation C30r lower lower lower lower lower Medicine Bow Formation Formation Lance Formation member member lower lower Lance Lance Lance Formation

member member member Lance Formation Formation Lance Formation Lance Formation Lance Formation member member Formation Formation Lance Formation C31n Lance Formation Hoploscaphites nicolletii Fox Hills Bobcat Lance Fox Hills Fox Hills Hoploscaphites birkelundae Member Formation Fox Hills Sandstone Sandstone Evanston Formation (part) Sandstone Meeteetse undifferentiated Fox Hills Ss Fox Hills Ss Formation 70 70.08 ± 0.37 Fox Hills Ss Fox Hills Ss Fox Hills Ss Fox Hills Ss Fox Hills clinolobatus “" balchii Fox Hills Ss upper part upper part upper part Fox Hills Ss Unit C C31r upper part upper part upper part Fox Hills Fox Hills upper part Sandstone Fox Hills Sandstone Sandstone Lewis 70.66 ± 0.66 Dad Sandstone Dad Bearpaw Shale Sandstone Baculites grandis Trochoceramus radiosus Member Dad Sandstone Dad Sandstone Dad Sandstone Sandstone Member Member Member Mbr Dad Ss Mbr upper Unit B lower Harebell Formation Whetstone Lewis Shale Lewis Shale sandstone Hams Fork Falls sandstone shale Fox Hills Conglomerate mbr member Sandstone "Inoceramus" incurvus Mancicorpus striatus Member Meeteetse Meeteetse Baculites baculus Member lower part Lewis Interval Biozone lower part Meeteetse Meeteetse Formation Formation Lewis Unit A Endocostea typica Lewis Shale lower part lower part lower part Shale Lewis Shale Lewis Shale Lewis Shale Lewis Shale Formation Formation Lewis Shale lower part 72.1 ± 0.2 Shale

Lewis Shale Kara Bentonitic Kara Bentonitic Baculites eliasi "Inoceramus" redbirdensis Edmontonian Almond Almond Tekla Sand Mbr shale C32n 72.50 ± 0.31 lower part Lewis Member Member Formation Formation Shale Almond Almond Almond Almond Richard Ss Mbr Baculites jenseni Almond Almond Lewis Shale "Inoceramus" oblongus Formation Formation Formation Formation Formation Formation shale shale shale Rocky Ridge and Bearpaw Larimer ss mbrs 73.41 ± 0.47 Baculites reesidei Canyon Canyon Creek Mbr Creek Mbr Pine Ridge Ss Pine Ridge Ss Pine Ridge Ss Pine Ridge Ss Pine Ridge Ss Teapot Ss Mbr Teapot Ss Mbr Teapot Ss Mbr Shale Teapot Ss Mbr Teapot Ss Mbr Baculites cuneatus lower mbr Pine Ridge Ss Pine Ridge Ss Pine Ridge Ss Teapot Ss Mbr 74.05 ± 0.39 Baculites compressus "Inoceramus" altus upper shale C32r Didymoceras cheyennense Monument Hill shale Meeteetse Bentonitic Mbr Exiteloceras jenneyi Formation 75 74.85 ± 0.43 Sphaeroceramus Didymoceras stevensoni pertenuiformis sandstone marine shale member

shale lower shale member shale shale

Didymoceras nebrascense marine mbr member shale Rusty Aquilapollenites Rusty zone Rusty zone zone undifferentiated 76.62 ± 0.51 quadrilobus Ericson Sandstone shale Baculites scotti Interval Biozone Rock River middle

Ericson Sandstone Hygiene member Trail Trail Allen Allen Allen Formation member Pierre Shale "Inoceramus" tenuilineatus Mesaverde Sandstone Member Member Ridge Ridge Allen Ridge nonmarine Mesaverde Formation Member Baculites reduncus Formation Mesaverde Formation Red Bird Red Bird Red Bird Judithian Ericson Ss Formation Formation Mesaverde Group Mesaverde Group Trail Formation Mesaverde Group Parkman member C33n Ridge Allen Mesaverde Group Member Allen Sandstone Parkman Silty Silty Silty Mesaverde Formation Mesaverde Group Formation Ridge Member Member Member Mesaverde Group Ridge Mesaverde Group Member Sandstone Mesaverde Group Pierre Shale Baculites gregoryensis Formation Mesaverde Fm Parkman Member Mesaverde Group Formation

middle Parkman Ss Sandstone ampanian Member Pierre Shale

middle sandstone member Mesaverde Formation Member C

Mesaverde Formation Mitten Mitten Baculites perplexus undifferentiated upper Wallace Creek Mitten sandstone shale Tongue Cody Sh shale lower member Mitten Member Member Black Shale shale sandstone Mesaverde Formation Cataceramus sandstone shale member, upper Member sandstone Haystack Member shale Hatfield Fales Ss part Baculites sp. (smooth) subcompressus Sandstone shale Haystack Hatfield Ss Hatfield Mountains Member Member Claggett shale Member Sandstone Formation Mountains Member shale Aquilapolenites Hatfield Ss Mbr Member Hatfield Ss Mbr Baculites asperiformis Gottsche Formation middle shale Sharon Springs senonicus Rock Espy Tongue, Espy Tongue, Espy Tongue, middle “Stray sandstone” Member 80 80.10 ± 0.61 tongue Steele Shale Seminoe Mbr Steele Shale Steele Shale equivalent? sandstone Mesaverde Group member member shale Haystack Mtns Fm Haystack Mtns Fm Baculites mclearni Haystack Mtns Fm Interval Biozone Springs McCourt Tongue Deep Creek Ss Mbr Deep Creek Ss Mbr Deep Creek Ss Mbr Judith Ardmore Ardmore Sharon Springs "Inoceramus" McCourt Tongue O’Brien Spring Ss Mbr Bentonite Baculites obtusus Formation O’Brien Spring Mbr shale River Sussex Member Coulson Tongue

80.62 ± 0.40 Haystack Mtns Fm azerbaydjanensis lower sandstone Bentonite Sandstone Member Brooks Tongue Bolten Ranch Mbr ss beds “Conant Creek Sussex Ss Mbr Gammon Baculites sp. (weak flank ribs) Black Butte Tongue Cow Creek Ss Mbr member shale shale Brooks Tongue Tapers Ranch Mbr Haystack Mountains Fm Steele tongue,” shale shale Ferruginous Mbr Minnies Gap Tongue Tapers Ranch Ss Mbr lower shale Shannon Ss Mbr shale Baculites sp. (smooth) shale sandstone Rock Springs Fm Rock Springs Fm Shale Shannon Ss Mbr Chimney Rock Tongue shale part Groat Ss Bed Groat Ss Bed sandstone shale Scaphites hippocrepis III shaley shaley “Alkali Butte Mbr” Gammon member 81.71 ± 0.51 member Blair Steele Shale Member Member C33r 81.84 ± 0.22 Cataceramus balticus Aquilan Cody “Fishtooth Scaphites hippocrepis II basal basal Formation Steele Steele Steele Cody basal ss mbr sandstone” shale lower Pseudoplicapolis Sohare Shale Cody upper shale shale Blair Fm Adaville Blair Fm sandstones Shale Shale Shale Shale 82.29 ± 0.34 newmanii Formation Steele Shale Steele sandy Formation Shale

Shale Gammon Member Scaphites hippocrepis I Interval Biozone upper member, Gammon Member upper upper sandy including “Sussex” Scaphites leei III shale shale member, Telegraph including and Creek shale “Shannon” Upper 83.6 ± 0.3 Sphenoceramus upper “Sussex” Beds 83.75 ± 0.11 Lazeart Ss Mbr Airport Sandstone Airport Sandstone sandstones lundbreckensis Member Member sandy and Gammon Member Desmoscaphites bassleri Hinshaw Mbr member “Shannon” 84.41 ± 0.24 Airport Sandstone sandstones upper 84.43 ± 0.15 Member 84.55 ± 0.24 Desmoscaphites erdmanni Smoky Hill

Cody Shale Chalk 85 Clioscaphites choteauensis Cody Shale Cody Shale Member Cordiceramus bueltenensis Niobrara Niobrara Niobrara middle Clioscaphites vermiformis Cody Shale Member Member Member Santonian 85.66 ± 0.19 85.84 ± 0.37 Niobrara Cody Shale lower Clioscaphites saxitonianus Cladoceramus Proteacidites retusus Shurtliff Baxter Shale Niobrara Niobrara Niobrara Niobrara Niobrara Niobrara Cody Shale Member undulatoplicatus Niobrara Cody Shale 86.3 ± 0.5 Interval Biozone Ss Mbr Formation Formation Formation Formation Formation Formation Niobrara 86.52 ± 0.33 Niobrara Formation Baxter Shale

Baxter Shale Formation Cretaceous (part) lower lower Formation Magadiceramus crenelatus lower shaly lower shaly shale shale member member upper 87.13 ± 0.19 Scaphites depressus Bacon Ridge lower shaly Niobrara Niobrara

Hilliard Shale Sandstone member Member Magadiceramus subquadratus Member

Volviceramus koeneni “chalk kick” “chalk kick” “chalk kick” middle Scaphites ventricosus Volviceramus involutus Cody Shale

Coniacian Cremnoceramus crassus Fort Hays Ls Mbr inconstans/crassus Fencelakian Sage Breaks Sage Breaks Sage Breaks Sage Breaks Wall Creek marine Shale Sage Breaks Wall Creek 89.32 ± 0.34 Scaphites preventricosus Shale Shale Shale Sage Breaks Member lower Cremnoceramus deformis sandstone Shale Shale Sage Breaks Member erectus/dobrogensis upper part Wall Creek equivalent? Sage Breaks member Dry Hollow/ Dry Hollow/ Dry Hollow/ Shale Member Member 89.8 ± 0.4 Wall Creek Mbr Wall Creek Sage Breaks Mbr Sage Breaks Mbr 89.87 ± 0.18 Wall Creek Mbr Wall Creek Mbr Wall Creek Wall Creek Wall Creek Wall Creek Wall Creek 90 Cremnoceramus Member Wall Creek Sage Breaks Member Wall Creek Mbr Member Member Member Member Wall Creek Wall Creek Sage Breaks Mbr upper waltersdorfensis – nonmarine Member Member Shale Member Turner Turner Codell Scaphites mariasensis – Inoceramus perplexus Turner Sandy Sandy Prionocyclus hyatti member Wall Creek Wall Creek Sandy Sandstone (7 Biozones, detailed below) Member Member Member (8 Biozones, detailed below) Member Carlile Member Carlile Sh Member 91.24 ± 0.23 Oyster Ridge/ Oyster Ridge/ Oyster Ridge/ Emigrant Emigrant Emigrant Member Emigrant Gap Mbr Emigrant Gap Mbr Emigrant Gap Mbr Emigrant Gap Mbr Emigrant Gap Mbr Emigrant Gap Mbr Emigrant Gap Mbr Dry Hollow Mbr Gap Mbr Gap Mbr Gap Mbr Emigrant Gap Mbr Emigrant Gap Mbr Inoceramus dimidius – marine Emigrant Gap Mbr Emigrant Gap praecox lower part Emigrant Carlile Shale sandstone Carlile Shale middle Mytiloides subhercynicus Member Gap Pool Creek Pool Creek and shale equivalent? Pool Creek Member Member (6 Biozones, detailed below) Nyssapolenites Oyster Ridge Member Member Collignoniceras woolgari abertensis Sandstone Mbr member sandstone Allen Hollow Interval Biozone Shale Mbr upper part Mammites nodosoides – Mytiloides mytiloides – Coalville Mbr Bridge Creek lower Watinoceras devonense Mytiloides puebloensis Greenhorn 93.67 ± 0.31 (4 Biozones, detailed below) (3 Biozones, detailed below) Formation Member

93.9 ± 0.2 93.79 ± 0.26 Frontier Formation Frontier Formation

94.10 ± 0.27 Frontier Formation

Frontier Formation sandstone Detailed Below Frontier Formation Frontier Formation 94.20 ± 0.28 Chalk Creek Frontier Formation Frontier Formation Frontier Formation Frontier Formation

C34n Frontier Formation Frontier Formation Frontier Formation Frontier Formation

Member Frontier Formation 94.43 ± 0.29 Frontier Formation Frontier Formation Greenhorn Greenhorn Frontier Formation

upper Nigericeras scotti – Mytiloides hattini – Frontier Formation Heartland Shale Formation Formation 95 Conlinoceras tarrantense Inoceramus eulessanus nonmarine Greenhorn Formation lower part Member Chalk member Soap Creek 95.32 ± 0.61 (15 Biozones, detailed below) (7 Biozones, detailed below) Creek Bentonite Lincoln Ls Mbr 95.53 ± 0.25 “Torchlight Ss Mbr” Belle Member Belle Belle Fourche middle Belle Belle Belle “Peay Ss Mbr” Thatcher Ls Belle Belle Fourche Fourche Belle Belle Belle Formation Belle Member 96.12 ± 0.31 Belle Belle Belle Fourche Fourche Fourche Belle Belle Belle Fourche Fourche Fourche Fourche Member Member Member Fourche Belle Fourche Fourche Bailey Flats Fourche Fourche Unzoned Fourche Member Member (core) Bent Fourche Fourche Graneros 96.56 ± 0.45 Unzoned Member Belle Member Member Member Member Fourche Member Member Belle Fourche Member Formation Member Member Formation Formation Shale Beattonoceras beattonense Fourche Member sandstone equivalent and shale Clay Spur Member Belle Fourche Mbr Ireniceras bahani Mussentuchian Bentonite Neogastroplites septimus Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Clay Spur Neogastroplites maclearni Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite (?) Bentonite Bentonite Bentonite Bentonite Bentonite Bentonite Neogastroplites americanus Cenomanian Gnesioceramus Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale lower Neogastroplites muelleri mowriensis Sage

dunveganensis Junction Neogastroplites cornutus Posidonioceramus Fm Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale Mowry Shale Aspen 99.26 ± 0.70 Shale 99.46 ± 0.59 Posidonioceramus Neogastroplites haasi Quealy Shell Creek Shell Creek Shell Creek Shell Creek Shell Creek Shell Creek Shell Creek Shell Creek Shell Creek Shell Creek 100 nahwisi Fm Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale 100.5 ± 0.4 Plicatella unica Cokeville Interval Biozone Fm Unzoned

Muddy Unzoned Muddy Muddy Muddy Muddy Muddy Muddy Muddy Muddy Muddy Muddy Muddy Muddy Muddy Muddy Muddy Muddy Muddy Muddy Muddy Muddy Newcastle Newcastle Sandstone/ Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone Sandstone “J sandstone” Bear upper Cashanranchian Thomas River Gnesioceramus Fork Fm comancheanus Fm Lower (part) (part)

Eopachydiscus marcianus Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Thermopolis Skull Creek Skull Creek Skull Creek Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale Shale Unzoned 105

CORRELATION CHART EXPLANATION ACKNOWLEDGMENTS REFERENCES Sincere thanks and appreciation to Kevin “Casey” McKinney for help with the U.S. Geological Survey’s Denver Cenomanian, Turonian, and Coniacian Stages: Detailed Certain age boundary Fm Formation Mesozoic Invertebrate Database. Reviews from Mark Kirschbaum, Robert Raynolds, Robert Scott, David Sawyer, 1. Bader, J.W., Gill, J.R., Cobban, W.A., and Law, B.E., 1983, Biostratigraphic correla- 27. Kauffman, E.G., 1977, Upper Cretaceous cyclothems, biotas, and environments, 52. Nichols, D.J., and Brown, J.L., 1992, Palynostratigraphy of the Tullock Member Mbr Member James Fox, Anton Wroblewski, and Donald Boyd were invaluable. tion chart of some Upper Cretaceous rocks from the Lost Soldier area, Wyoming Rock Canyon anticline, Pueblo, : The Mountain Geologist, v. 14, nos. (lower ) of the Fort Union Formation in the Powder River Basin, Uncertain or interpreted age boundary Ss Sandstone to west of Craig, Colorado: U.S. Geological Survey Miscellaneous Field Studies 3–4, p. 129–152. and Wyoming: U.S. Geological Survey Bulletin 1917-F, 35 p., 10 pls. REQUEST FROM AUTHORS Map 1548. Age Period Epoch Stages and Stage Polarity U.S. Western Interior U.S. Western Interior U.S. Western Interior North American U.S. Western Interior Bentonite—Named when known Ls Limestone 28. Kirschbaum, M.A., Merewether, E.A., and Condon, S.M., 2009, and 53. Nichols, D.J., and Jacobson, S.R., 1982, Cretaceous biostratigraphy in the Wyoming (Ma) Boundary Chron Radiometric Ammonite Inoceramid Land Vertebrate Palynostratigraphic Sh Shale This publication is a work in progress that will be updated periodically. The authors request notice of any new or 2. Cifelli, R.L., Eberle, J.J., Lofgren, D.L., Lillegraven, J.A., and Clemens, W.A., 2004, age of the Frontier Formation and associated rocks, central and southern Bighorn thrust belt: The Mountain Geologist, v. 19, no. 3, p. 73–78. Maximum missing or condensed section Mammalian biochronology of the latest Cretaceous, in Woodburne, M.W., ed., Basin, Wyoming—Surface to subsurface correlation: The Mountain Geologist, (Ma) Age (Ma) Biozone Biozone Age Biozone Bent Bentonite revised data that will enhance the accuracy of the interpretations presented in this chart. 54. Obradovich, J.D., 1993, A Cretaceous time scale, in Caldwell, W.G.E., and Kauff- and Cenozoic mammals of : New York, Colum- v. 46, no. 4, p. 125–147. man, E.G., eds., Evolution of the Western Interior Basin: Geological Association ? Uncertain formation name bia University Press, p. 21–42. 29. Kirschbaum, M.A., and Roberts, L.N.R., 2005a, Geologic assessment of undiscov- of Canada Special Paper 39, p. 379–396. (7, 56, 74) (7, 56, 74) (8, 49, 54, 55, 56, 69, 72) (7, 23, 25, 56, 74) (7, 56, 74) (2, 33, 35, 77) (50) DISCLAIMERS 3. Cobban, W.A., 1990, Ammonites and some characteristic bivalves from the Upper ered oil and gas resources in the Mowry composite total petroleum system, 55. Obradovich, J.D., and Cobban, W.A., 1975, A time-scale for the Late Cretaceous of 86 “ ” Unofficial formation or member name Users of these cross sections and maps are cautioned against using the data at scales different from those at which Cretaceous Frontier Formation, Natrona County, Wyoming: U.S. Geological southwestern Wyoming Province, Wyoming, Colorado, and , chap. 5 of Clioscaphites saxitonianus Cladoceramus the Western Interior of North America: in Caldwell, W.G.E., ed., The Cretaceous the data were compiled. Using these data at a larger scale will not provide greater accuracy and is a misuse of the Survey Bulletin 1917, chap. B, 13 p., 11 pls. U.S. Geological Survey Southwest Wyoming Province Assessment Team, (part) undulatoplicatus Terrestrial and transitional marine depositional environment (generalized) system in the Western Interior of North America: Geological Association of 86.3 ± 0.5 data. 4. Cobban, W.A., and Larson, N.L., 1997, Marine Upper Cretaceous rocks and their comp., Petroleum systems and geologic assessment of oil and gas in the Canada Special Paper 13, p. 31–54. 86.52 ± 0.33 (part) southwestern Wyoming Province, Wyoming, Colorado, and Utah: U.S. Geologi- Nearshore to transitional marine depositional environments (generalized) The Wyoming State Geological Survey (WSGS) and the State of Wyoming make no representation or warranty, ammonite record along the northern flank of the Black Hills Uplift, Montana, 56. Ogg, J.G., and Hinnov, L.A., 2012, Cretaceous, in Gradstein, F.M., Ogg, J.G., cal Survey Digital Data Series 69-D, 23 p. Magadiceramus expressed or implied, regarding the use, accuracy, or completeness of the data presented herein, or of a map printed Wyoming, and : University of Wyoming Contributions to , Schmitz, M.D., and Ogg, G.M., eds., The geologic time scale 2012: Amsterdam, Offshore depositional environment (generalized) from these data. The act of distribution shall not constitute such a warranty. The WSGS does not guarantee the v. 32, no. 1, p. 27–35. 30. Kirschbaum, M.A., and Roberts, L.N.R., 2005b, Stratigraphic framework of the Elsevier B.V., p. 793–853. crenelatus Cretaceous Mowry Shale, Frontier Formation and adjacent units, southwestern 87.13 ± 0.19 Approximate location of radiometric age sample digital data or any print made from the data to be free of errors or inaccuracies. 5. Cobban, W.A., and Reeside, J.B., Jr., 1951, Frontier Formation near Sinclair, Carbon 57. Perman, R.C., 1988, Stratigraphy and sedimentology of the Lewis Shale and the Fox upper Scaphites depressus County, Wyoming: Wyoming Geological Association, 6th annual field confer- Wyoming Province, Wyoming, Colorado, and Utah, chap. 15 of U.S. Geological Proteacidites retusus The WSGS and the State of Wyoming disclaim any responsibility or liability for interpretations made from these Hills Formation in south-central Wyoming: Berkeley, University of California, ence, Guidebook, p. 60–65. Survey Southwest Wyoming Province Assessment Team, comp., Petroleum Ph.D. dissertation, 256 p. Magadiceramus Interval Biozone digital data or from any print made from these digital data, and for any decisions based on the digital data or printed systems and geologic assessment of oil and gas in the southwestern Wyoming subquadratus (part) publication. The WSGS and the State of Wyoming retain and do not waive sovereign immunity. 6. Cobban, W.A., and Reeside, J.B., Jr., 1952, Frontier Formation, Wyoming and 58. Pyles, D.R., and Slatt, R.M., 2007, Stratigraphy of the Lewis Shale, Wyoming, adjacent areas: American Association of Petroleum Geologists Bulletin, v. 36, Province, Wyoming, Colorado, and Utah: U.S. Geological Survey Digital Data ADDITIONAL INFORMATION Series 69-D, 31 p. USA—Applications to understanding shelf-edge to base-of-slope changes in The use of or reference to trademarks, trade names, or other product or company names in this publication is for no. 10, p. 1,913–1,961. stratigraphic architecture of prograding basin margins, in Nilsen, T.H., Shew, descriptive or informational purposes only, or is pursuant to licensing agreements between the WSGS or State of 31. Kiteley, L.W., 1976, Marine and sandstones in the Upper Cretaceous Pierre The approximate location of each stratigraphic column is shown with the corresponding letter on the 7. Cobban, W.A., Walaszczyk, Ireneusz, Obradovich, J.D., and McKinney, K.C., 2006, R.D., Steffens, G.S., and Studlick, J.R.J., eds., Atlas of deepwater outcrops: Volviceramus koeneni Wyoming and software or hardware developers/vendors, and does not imply endorsement of those products by the A USGS zonal table for the Upper Cretaceous middle Cenomanian–Maastrich- Shale at the Francis Ranch, Laramie County, Wyoming: The Mountain Geolo- American Association of Petroleum Geologists, Studies in Geology 56, chap. map. WSGS or the State of Wyoming. gist, v. 13, no. 1, p. 1–19. Scaphites ventricosus tian of the Western Interior of the based on ammonites, inocera- 113, p. 485–489. middle Volviceramus involutus 32. Leier, A.L., and Steidtmann, J.R., 2009, The Bacon Ridge Sandstone of northwestern References used to determine formation ages for each column are listed as numbers below the gener- mids, and radiometric ages: U.S. Geological Survey Open-File Report 59. Reeside, J.B., and Cobban, W.A., 1960, Studies of the Mowry Shale (Cretaceous) 2006-1250, 46 p., 1 pl. Wyoming and its place within the larger-scale Late Cretaceous depositional alized column name and correspond to the numbered references. NOTICE TO USERS OF INFORMATION FROM THE WYOMING STATE GEOLOGICAL SURVEY and contemporary formations in the United States and Canada: U.S. Geological Coniacian Cremnoceramus crassus inconstans 8. Clyde, W.C., Ramezani, Jahandar, Johnson, K.R., Bowring, S.A., and Jones, M.M., history of the region: The Mountain Geologist, v. 46, no. 2, p. 51–70. Survey Professional Paper 355, 126 p., 58 pls. The WSGS encourages the fair use of its material. We request that credit be expressly given to the “Wyoming State Wyoming’s stratigraphic nomenclature can be inconsistent, especially near the borders with 2016, Direct high-precision U-Pb geochronology of the end-Cretaceous extinc- 33. Lillegraven, J.A., and Ostresh, L.M., 1990, Late Cretaceous (earliest Campan- 60. Reynolds, M.W., 1976, Influence of recurrent Laramide structural growth on Cremnoceramus crassus crassus Geological Survey” when citing information from this publication. Please contact the WSGS at 307-766-2286, ext. tion and calibration of Paleocene astronomical timescales: Earth and Planetary ian/Maastrichtian) evolution of western shorelines of the North American surrounding states. The nomenclature used in this chart is from Love and others (1993) in locations 224 or by email at [email protected] if you have questions about citing materials, preparing acknowledgments, sedimentation and petroleum accumulation, Lost Soldier area, Wyoming: Amer- Science Letters, v. 452, p. 272–280. in relation to known mammalian faunas, in Bown, ican Association of Petroleum Geologists Bulletin, v. 60, no. 1, p. 12–33. lower 89.32 ± 0.34 Scaphites preventricosus Cremnoceramus deformis erectus where multiple terminologies are used. or extensive use of this material. We appreciate your cooperation. T.M., and Rose, K.D., eds., Dawn of the age of mammals in the northern part of 9. Demar, D.G., Jr., and Breithaupt, B.H., 2006, The nonmammalian vertebrate micro- 61. Robinson, C.S., Mapel, W.J., and Bergendahl, M.H., 1964, Stratigraphy and structure Martin and others (2007) proposed raising the rank of the Pierre Shale from formational to group Individuals with disabilities who require an alternative form of this publication should contact the WSGS. For the assemblages of the Mesaverde Formation (Upper Cretaceous, ) the Rocky Mountain Interior, North America: Geological Society of America Cremno. deformis dobrogensis Special Paper 243, p. 1–30. of the northern and western flanks of the Black Hills Uplift, Wyoming, Montana, level and consequently raised its members to formational status. To maintain consistency with TTY relay operator, call 800-877-9975. of the Wind River and Bighorn basins, Wyoming, in Lucas, S.G., and Sullivan, and South Dakota: U.S. Geological Survey Professional Paper 404, 134 p., 5 pls. Scaphites mariasensis Cremno. walterdorfensis Fencelakian 34. Love, J.D., Christiansen, A.C., and Ver Ploeg, A.J., comps., 1993, Stratigraphic chart 89.8 ± 0.4 89.87 ± 0.18 previously published literature on the Pierre Shale, this chart retains the former nomenclature follow- For more information about the WSGS or to order publications and maps, go to www.wsgs.wyo.gov, call R.M., eds., Late Cretaceous from the Western Interior: 62. Roehler, H.W., 1978, Correlations of beds in the Fort Union, Almond, and Rock 90 Prionocyclus germari Mytiloides scupini (part) Museum of Natural History and Science Bulletin 35, p. 33–53. showing the Phanerozoic nomenclature for the state of Wyoming: Geological ing Love and others (1993). 307-766-2286, ext. 224, or email [email protected]. Survey of Wyoming [Wyoming State Geological Survey] Map Series 41. Springs formations in measured sections on the west flank of the Rock Springs Scaphites nigricollensis Mytiloides incertus 10. Dorr, J.A., Jr., 1985, Newfound and other in Uplift, Sweetwater County, Wyoming: U.S. Geological Survey Open-File upper Inoceramus dakotensis southeastern and westernmost Wyoming: Contributions from the Museum 35. Lucas, S.G., Sullivan, R.M., and Spielmann, J.A., 2012, Cretaceous vertebrate Report 78-395. Scaphites whitfieldi Inoceramus perplexus of Paleontology, University of Michigan, v. 27, no. 3, p. 73–85. biochronology, North American Western Interior: Journal of Stratigraphy, v. 36, no. 2, p. 436–461. 63. Roehler, H.W., 1983, Stratigraphy of Upper Cretaceous and lower Tertiary outcrops 11. Dorr, J.A., Jr., Spearing, D.R., and Steidtmann, J.R., 1977, Deformation and deposi- in the Rock Springs Uplift, Wyoming: U.S. Geological Survey Miscellaneous Scaphites ferronensis 36. Lynds, R.M., and Lichtner, D.T., 2016, Stratigraphy and hydrocarbon potential of the Inoceramus dimidius 111°W 110°W 109°W 108°W 107°W 106°W 105°W 104°W tion between a foreland uplift and an impinging thrust belt—Hoback Basin, Investigations Series Map I-1500. Fort Union and Lance Formations in the Great Divide and Washakie Basins, Scaphites warreni 45°N 45°N Wyoming: Geological Society of America Special Paper 177, 82 p. 64. Roehler, H.W., 1990, Stratigraphy of the Mesaverde Group in the central and eastern 91.24 ± 0.23 12. Eicher, D.L., 1960, Stratigraphy and micropaleontology of the Thermopolis Shale: south-central Wyoming: Wyoming State Geological Survey Report of Investiga- Prionocyclus macombi Inoceramus aff. dimidius tions 73, 70 p., 2 pls. Greater Green River Basin, Wyoming, Colorado, and Utah: U.S. Geological Yale University, Peabody Museum of Natural History Bulletin 15, 126 p., 6 pls. Survey Professional Paper 1508, 52 p., 2 pls. Prionocyclus hyatti Inoceramus howelli Sheridan X 13. Finn, T.M., 2007, Source rock potential of Upper Cretaceous marine shales in the 37. Malone, David, 2017, Unpublished detrital zircon data. Powell 3 65. Rubey, W.W., 1973, New Cretaceous formations in the western Wyoming thrust belt: 3 Wind River Basin, Wyoming, chap. 8 of U.S. Geological Survey Wind River 38. Martin, J.E., Bertog, J.L., and Parris, D.C., 2007, Revised of the U.S. Geological Survey Bulletin 1372-I, 135 p. Collignoniceras praecox S lower Pierre Shale Group (Campanian) of central South Dakota, including newly Inoceramus n. sp. Basin Province Assessment Team, comp., Petroleum systems and geologic 66. Rubey, W.W., Oriel, S.S., and Tracey, J.I., Jr., 1961, Age of the Evanston Formation, middle assessment of oil and gas in the Wind River Basin Province, Wyoming: U.S. designated members, in Martin, J.E., and Parris, D.C., eds., The geology and Cody western Wyoming: Wyoming Geological Association, 16th annual field confer- 3 Black Hills paleontology of the Late Cretaceous marine deposits of the Dakotas: Geological Geological Survey Digital Data Series 69-J, 24 p. ence, Guidebook, p. 68–69. Mytiloides hercynius Nyssapolenites R 14. Finn, T.M., and Pawlewicz, M.J., 2013, Maps showing thermal maturity of Upper Society of America Special Paper 427, p. 9–22.

Turonian 67. Rudolph, K.W., Devlin, W.J., and Crabaugh, J.P., 2015, Upper Cretaceous sequence abertensis Uplift Cretaceous marine shales in the Wind River Basin, Wyoming: U.S. Geological 39. Mellere, D.A., and Steele, R.J., 1995, Facies architecture and sequentiality of Collignoniceras woolgari Gillette stratigraphy of the Rock Springs Uplift, Wyoming: The Mountain Geologist, v. Mytiloides subhercynius Interval Biozone 3 Survey Scientific Investigations Map 3266, 13 p., 1 pl., scale 1:500,000. nearshore and ‘shelf’ sandbodies; Haystack Mountains Formation, Wyoming, BIGHORN USA: Sedimentology, v. 42, p. 551–574. 52, no. 3, p. 13–157. 15. Gill, J.R., 1974, Stratigraphic sections of the Mesaverde Group, Lewis Shale, Fox 68. Runge, J.S., Wicker, W.L., and Eckelberg, D.J., 1973, A subsurface type section of Hills Formation, and Medicine Bow Formation, Carbon County, Wyoming: U.S. 40. Merewether, E.A., 1996, Stratigraphy and tectonic implications of Upper Cretaceous Mammites nodosoides BASIN POWDER the Teckla Sand Member of the Lewis Shale Formation: Wyoming Geological C34n Mytiloides mytiloides 44°N Worland 44°N Geological Survey Open-File Report 74-1038, 4 sheets. rocks in the Powder River Basin, northeastern Wyoming and southeastern 3 Montana: U.S. Geological Survey Bulletin 1917-T, 92 p. Association Earth Science Bulletin, v. 6, no. 3, p. 3–18. (part) Vascoceras birchbyi RIVER 16. Gill, J.R., and Cobban, W.A., 1966, Regional in Late Cretaceous, 69. Sageman, B.B., Singer, B.S., Meyers, S.R., Siewert, S.E., Walaszczyk, Ireneusz, lower Mytiloides kossmati Wyoming: U.S. Geological Survey Professional Paper 550-B, p. B20–B27. 41. Merewether, E.A., and Cobban, W.A., 1972, within the Frontier Pseudaspidoceras flexuosum Condon, D.J., Jicha, B.R., Obradovich, J.D., and Sawyer, D.A., 2014, Integrat- JACKSON W 17. Gill, J.R., and Cobban, W.A., 1973, Stratigraphy and geologic history of the Montana Formation, northwestern Carbon County, Wyoming: U.S. Geological Survey Upper (part) 93.67 ± 0.31 Mytiloides puebloensis BASIN Professional Paper 800-D, p. D57–D66. ing 40Ar/39Ar, U-Pb, and astronomical clocks in the Cretaceous Niobrara 93.79 ± 0.26 Watinoceras devonense Group and equivalent rocks, Montana, Wyoming, and North and South Dakota: Formation, Western Interior Basin, USA: Geological Society of America Cretaceous (part) 93.9 ± 0.2 HOLE U.S. Geological Survey Professional Paper 776, 37 p. 42. Merewether, E.A., and Cobban, W.A., 1973, Stratigraphic sections of the Upper Nigericeras scotti Mytiloides hattini Bulletin, v. 126, nos. 7–8, p. 956–973. 94.10 ± 0.27 18. Gill, J.R., Cobban, W.A., and Kier, P.M., 1966, The Red Bird section of Upper Cretaceous Frontier Formation near Casper and Douglas, Wyoming: Wyoming 94.20 ± 0.28 Neocardioceras juddii B Geological Association Earth Science Bulletin, v. 6, no. 4, p. 38–39. 70. Schlaikjer, E.M., 1935, Contributions to the stratigraphy and palaeontology of the Burroceras clydense Inoceramus pictus Cretaceous Pierre Shale in Wyoming: U.S. Geological Survey Professional Goshen Hole area, Wyoming. II. The Torrington Member of the Lance Forma- 94.43 ± 0.29 Paper 393-A, 69 p., 12 pls. 43. Merewether, E.A., and Cobban, W.A., 1986, Biostratigraphic units and tectonism in Euomph. septemseriatum T tion and a study of a new : Harvard College, Museum of Comparative 19. Gill, J.R., Merewether, E.A., and Cobban, W.A., 1970, Stratigraphy and nomencla- the mid-Cretaceous foreland of Wyoming, Colorado, and adjoining areas, in Zoology Bulletin, v. 76, p. 31–68. upper Vascoceras diartianum Peterson, J.A., ed., Paleotectonics and sedimentation in the Rocky Mountain Dunveganoceras conditum ture of some Upper Cretaceous and lower Tertiary rocks in south-central 71. Schmitz, M.D., 2012, Radiometric ages used in GTS2012—Appendix 2, in Inoceramus ginterensis V Wyoming: U.S. Geological Survey Professional Paper 667, 53 p. region, United States: American Association of Petroleum Geologists Memoir 95 Dunveganoceras albertense WIND RIVER BASIN 41, p. 443–468. Gradstein, F.M., Ogg, J.G., Schmitz, M.D., and Ogg, G.M., eds., The geologic O Riverton 20. Gomez-Veroiza, C.A., and Steele, R.J., 2010, Iles clastic wedge development and time scale: Amsterdam, Elsevier B.V., p. 1,045–1,082. Dunveg. problematicum 43°N HOBACK 3 Q U 43°N 44. Merewether, E.A., Cobban, W.A., and Cavanaugh, E.T., 1979, Frontier Formation 95.32 ± 0.61 sediment partitioning within a 300-km fluvial to marine Campanian transect (3 72. Smith, J.H., 1965, A summary of stratigraphy and paleontology, upper Colorado and Dunveganoceras pondi Inoceramus prefragilis BASIN m.y.), Western Interior Seaway, southwestern Wyoming and northern Colorado: and equivalent rocks in eastern Wyoming: The Mountain Geologist, v. 16, no. 3, 95.53 ± 0.25 P p. 67–101. Montanan Groups, southcentral Wyoming, Northeastern Utah, and northwestern Plesiacanth. wyomingense Lander Casper American Association of Petroleum Geologists Bulletin, v. 94, no. 9, p. Colorado: Wyoming Geological Association, 19th annual field conference, Acanthoceras amphibolum Inoceramus rutherfordi 3 3 1,349–1,377. 45. Merewether, E.A., Cobban, W.A., and Obradovich, J.D., 2007, Regional disconfor- 3 Guidebook, p. 13–26, 4 pls. middle Acanthoceras bellense Inoceramus arvanus Douglas mities in Turonian and Coniacian (Upper Cretaceous) strata in Colorado, 21. Hale, L.A., 1961, Late Cretaceous (Montanan) stratigraphy, eastern Washakie Basin, 73. Walaszczyk, Ireneusz, and Cobban, W.A., 2000, Inoceramid faunas and biostratigra- Acanthoceras muldoonense Inoceramus eulessanus Carbon County, Wyoming: Wyoming Geological Association, 16th annual field Wyoming, and adjoining states—Biochronological evidence: Rocky Mountain 96.12 ± 0.31 Acanthoceras granerosense Geology, v. 42, no. 2, p. 95–122. phy of the Upper Turonian–Lower Coniacian of the Western Interior of the conference, Guidebook, p. 129–137. United States: Paleontological Association, Special Papers in Palaeontology, no. Conlinoceras tarrantense 46. Merewether, E.A., Cobban, W.A., and Obradovich, J.D., 2011, Biostratigraphic data Unzoned 22. Harris, J.D., Johnson, K.R., Hicks, J., and Tauxe, L., 1996, Four-toed theropod 64, 118 p., 32 pls. 96.56 ± 0.45 Unzoned from Upper Cretaceous formations—Eastern Wyoming, central Colorado, and L SHIRLEY footprints and a paleomagnetic age from the Whetstone Falls Member of the 74. Walaszczyk, Ireneusz, and Cobban, W.A., 2016, Inoceramid bivalves and biostratig- Harebell Formation (Upper Cretaceous: Maastrichtian), northwestern Wyoming: northeastern New Mexico: U.S. Geological Survey Scientific Investigations K BASIN Map 3175, 10 p., 2 pls. raphy of the upper Albian and lower Cenomanian of the United States Western Beattonoceras beattonense J Cretaceous Research, v. 17, p. 381–401. Interior Basin: Cretaceous Research, v. 59, p. 30–68. 47. Merewether, E.A., and McKinney, K.C., 2015, Chronostratigraphic cross section of Torrington 23. Hoganson, J.W., and Murphy, E.C., 2002, Marine Breien Member (Maastrichtian) of 75. Wallem, D.B., Steidtmann, J.R., and Surdam, R.C., 1981, Depositional environments Ireniceras bahani 3 Cretaceous formations in western Montana, western Wyoming, eastern Utah, Mussentuchian GREEN RIVER BASIN I the in —Stratigraphy, vertebrate fossil and diagenesis of the Bear River Formation, western Wyoming: Wyoming 42°N 42°N northeastern Arizona, and northwestern New Mexico, U.S.A.: U.S. Geological Neogastroplites septimus GREAT DIVIDE BASIN record, and age, in Hartman, J.H., Johnson, K.R., and Nichols, D.J., eds., The Geological Association, 32nd annual field conference, Guidebook, p. 23–39. HANNA Hell Creek Formation and the Cretaceous–Tertiary boundary in the northern Survey Open-File Report 2015-1087, 10 p., 1 pl. H 48. Moredock, Duane, McClure, Dan, Matuszczak, Pete, and Bortz, Lou, 1977, Denver 76. Weimer, R.J., 1960, Upper Cretaceous stratigraphy, Rocky Mountain area: American Neogastroplites maclearni BASIN —An integrated continental record of the end of the Cretaceous: Association of Petroleum Geologists Bulletin, v. 44, no. 1, 20 p. Y Geological Society of America Special Paper, 361, p. 247–270. Basin, in Irwin, Dennis, comp., Subsurface cross sections of Colorado: Rocky A C Rawlins 3 M N 77. Wilson, G.P., Dechesne, Marieke, and Anderson, I.R., 2010, New latest Cretaceous Cenomanian Neogastroplites americanus 24. Hutsky, A.J., Fielding, C.R., Hurd, T.J., and Clark, C.K., 2012, Sedimentology and Mountain Association of Geologists Special Publication 2, 5 p., 6 pls. Rock Rock mammals from northeastern Colorado with biochronologic and biogeographic Plicatella unica Springs G DENVER stratigraphy of the Upper Cretaceous (Cenomanian) Frontier Formation, 49. Meyers, S.R., Siewert, S.E., Singer, B.S., Sageman, B.B., Condon, D.J., Obradovich, Gnesioceramus 3 Springs E J.D., Jicha, B.R., and Sawyer, D.A., 2012, Intercalibration of radioisotopic and implications: Journal of Vertebrate Paleontology, v. 30, no. 2, p. 499–520. dunveganensis Interval Biozone northeast , Wyoming, U.S.A.: The Mountain Geologist, v. 49, no. lower mowriensis 3 BASIN 78. Wroblewski, A.F.-J., 2002, The role of the Hanna Basin in revised paleogeographic Neogastroplites muelleri Posidonioceramus Green Uplift 3, p. 77–98. astrochronologic time scales for the Cenomanian–Turonian boundary interval, (part) River LARAMIE reconstructions of the Western Interior Sea during the Cretaceous-Tertiary 25. Johnson, K.R., Nichols, D.J., and Hartman, J.H., 2002, Hell Creek Formation—A Western Interior Basin, USA, Geology, v. 40, no. 1, p. 7–10. F BASIN transition: Wyoming Geological Association, 53rd field conference, Guidebook, Evanston BRIDGER BASIN WASHAKIE BASIN 3 2001 synthesis, in Hartman, J.H., Johnson, K.R., and Nichols, D.J., eds., The 50. Nichols, D.J., 1994, A revised palynostratigraphic zonation of the nonmarine Upper 3 p. 17–40. Neogastroplites cornutus Laramie Hell Creek Formation and the Cretaceous–Tertiary boundary in the northern Cretaceous, Rocky Mountain region, United States, in Caputo, M.V., Peterson, Cheyenne J.A., and Franczyk, K.J., eds., Mesozoic systems of the Rocky Mountain region, D 3 Great Plains—An integrated continental record of the end of the Cretaceous: Geological Society of America Special Paper 361, p. 503–510. USA: Denver, Rocky Mountain Section, SEPM, p. 503–521. 99.26 ± 0.70 41°N 41°N 26. Jump, C.J., and Ethridge, F.G., 1996, Stratigraphic and facies relationships within the 51. Nichols, D.J., 1998, Palynological age determinations of selected outcrop samples 99.46 ± 0.59 from the Lance and Fort Union formations in the Bighorn Basin, Montana and 111°W 110°W 109°W 108°W 107°W 106°W 105°W 104°W Late Cretaceous Frontier Formation, Rock Springs Uplift area, southwestern Posidonioceramus Wyoming—Paleozoic and Mesozoic stratigraphy of southwestern Wyoming, Wyoming: Wyoming Geological Association, 49th annual field conference, Neogastroplites haasi Layout by James R. Rodgers nahwisi Cretaceous outcrop Generalized location of northeastern Utah, and northwestern Colorado: Rocky Mountain Section SEPM Guidebook, p. 117–129. 100 0 5 10 20 30 40 50 60 Edited by Suzanne C. Luhr Legend outcrop column with corresponding ¯ fall field trip, p. 30–35. Basin letter Miles 100.5 ± 0.4