WYOMING STATE GEOLOGICAL SURVEY Wind/Bighorn River Basin Plan II Plate V Thomas A. Drean, State Geologist Available Groundwater Determination Technical Memorandum Geologic units/ Lithostratigraphic units/ Hydrogeologic units { { { { { { { Plate{ I { { Plate{ III { Plate II Plates IV and X Geologic unit Wyoming lithostratigraphic unit(s) Montana lithostratigraphic unit(s) as Hydrogeologic Unit named for their Wyoming Bighorn Basin and Wind River Basin and Symbol Age & general lithology Wyoming state map unit Bighorn River Basin Wind River Basin equivalents Absaroka/Yellowstone Volcanic unit Absaroka/Yellowstone Volcanic unit Wyoming Montana** CENOZOIC UNITS Water Water Water (surface) Water (surface) Water (surface) Water (surface) Water (surface) Water Water Aqu Ice – Glacial ice Glacial ice – Glacial ice – Ice – – – Qa Qa Pleistocene-Holocene alluvium & Alluvium & colluvium Alluvium & colluvium Alluvium & colluvium Alluvium & colluvium Qa Qa colluvium Qt Qt Pleistocene-Holocene unconsolidated Gravel, pediment, & fan deposits Gravel, pediment, & fan deposits Gravel, pediment, & fan deposits Gravel, pediment, & fan deposits Qt Qt deposits Aqu Quaternary unconsolidated deposit Aqu Quaternary unconsolidated deposit Qg Qg Pleistocene-Holocene glacial deposits Glacial deposits Glacial deposits Glacial deposits Glacial deposits aquifers aquifers Qg Qg Qls – Pleistocene-Holocene landslide & Landslide deposits Landslide deposits Landslide deposits – Qls – – glacial drift Qs – Pleistocene-Holocene dune sand & Dune sand & loess deposits – Dune sand & loess deposits – Qs – – – loess Quaternary units Quaternary Ql – Pleistocene-Holocene clay, silt, & fine Playa lake or marine deposits – Playa lake or marine deposits – Ql – – – sand Qu Qu Pleistocene-Holocene alluvium & Undivided surficial deposits Undivided surficial deposits – Undivided surficial deposits Qu Qu – Aqu Quaternary unconsolidated deposit colluvium deposits aquifers Qb – Pleistocene basalt & intrusive rocks Basalt flows & intrusive igneous Basalt flows & intrusive igneous Basalt flows & intrusive igneous – Qb – – undefined volcanic hydrogeologic undefined volcanic hydrogeologic rocks rocks rocks unit(s)2 unit(s)2 Qr – Pleistocene rhyolite & lava flow rocks Rhyolite flows, tuff, & intrusive Rhyolite flows, tuff, & intrusive – – Qr – – – Ayv igneous rocks igneous rocks Yellowstone Volcanic Group QTg – Pliocene-Pleistocene gravel deposit Terrace gravels Terrace gravels – – QTg – – – Aqu Quaternary unconsolidated deposit aquifers Thr Thr Pliocene rhyolite & tuff rocks Huckleberry Ridge Tuff of Huckleberry Ridge Tuff of – Huckleberry Ridge Tuff of Thr Thr – Ayv Yellowstone Group Yellowstone Group Yellowstone Group Yellowstone Volcanic Group Tii – Miocene-Pliocene granitoid & basalt Intrusive & extrusive igneous rocks Intrusive & extrusive igneous rocks – – Tii – – – undefined volcanic hydrogeologic rocks unit(s)2 Tcv – Miocene-Pliocene dacitic & felsic Caldwell Canyon Volcanics – Caldwell Canyon Volcanics – Tcv – – – undefined volcanic hydrogeologic volcanic rocks unit(s)2 Tmu – Upper Miocene sandstone & claystone Upper Miocene rocks (undivided) – Upper Miocene rocks (undivided) – Tmu – – – Tm – Miocene sandstone & conglomerate Miocene rocks (undivided) – Miocene rocks (undivided) – Tm – – – Asr Split Rock aquifer Tml – Lower Miocene sandstone (includes Lower Miocene (undivided) Lower Miocene (undivided) Lower Miocene (undivided) – Tml – – undefined Tertiary hydrogeologic Split Rock Formation) unit(s)2 Twr – Oligocene fine & medium-grained White River Formation White River Formation White River Formation – Twr – – Awh Awh mixed clastic White River aquifer White River aquifer Ti Ti Eocene plutonic rocks Intrusive igneous rocks Intrusive igneous rocks Intrusive igneous rocks Intrusive igneous rocks Ti Ti undefined Tertiary hydrogeologic undefined Tertiary hydrogeologic unit(s) 2 unit(s) 2 Tts Tts Eocene andesitic & pyroclastic rocks Thorofare Creek & Sunlight Thorofare Creek & Sunlight – Thorofare Creek & Sunlight Tts Tts – Groups Groups Groups Twi – Eocene mixed clastic/volcanic rocks Wiggins Formation Wiggins Formation Wiggins Formation – Twi – – Aav Absaroka Volcanic Supergroup Aav Absaroka Volcanic Supergroup Ttl – Eocene mixed clastic/volcanic & Two Ocean & Langford Two Ocean & Langford – – Ttl – – – intermediate volcanic rocks Formations Formations Tt – Eocene mixed clastic/volcanic & Tepee Trail Formation Tepee Trail Formation Tepee Trail Formation – Tt – – medium-grained mixed clastic undefined volcanic hydrogeologic Cwb Aycross-Wagon Bed confining Ta – Eocene mixed clastic/volcanic & fine- Aycross Formation Aycross Formation Aycross Formation – unit(s) 2 unit Ta – – grained mixed clastic Ts Ts Eocene intermediate volcanic & basalt Cresent Hill Basalt of Sunlight Cresent Hill Basalt of Sunlight – Cresent Hill Basalt of Sunlight Ts Ts – rocks Group Group Group Aav Absaroka Volcanic Supergroup Ttp – Eocene trachyandesite rocks Trout Peak Trachyandesite Trout Peak Trachyandesite – – Ttp – – – Tertiary units Twp Twp Eocene mixed clastic/volcanic & Wapiti Formation Wapiti Formation – Wapiti Formation Twp Twp – undefined volcanic hydrogeologic intermediate volcanic rocks unit(s) 2 Taw Taw Eocene mixed clastic/volcanic & Washburn Group Washburn Group – Washburn Group Taw Taw – Aav intermediate volcanic rocks Absaroka Volcanic Supergroup Twb – Eocene claystone & conglomerate Wagon Bed Formation Wagon Bed Formation Wagon Bed Formation – Aycross-Wagon Bed confining Twb – – Awb Wagon Bed aquifer Cwb unit Tv – Eocene conglomerate & mixed Volcanic conglomerate – Volcanic conglomerate – Tv – – – undefined volcanic hydrogeologic clastic/volcanic rocks unit(s) 2 Tcr – Eocene conglomerate Crandall Conglomerate Crandall Conglomerate – – Tcr – – – undefined Tertiary hydrogeologic unit(s)2 Twdr – Eocene claystone & siltstone Wind River Formation – Wind River Formation – Twrd – – – Awr Wind River aquifer Twim – Eocene fine-grained mixed clastic & Wind River & Indian Meadows – Wind River & Indian Meadows – Twim – – – undifferentiated Tertiary geologic medium-grained mixed clastic rocks Formations Formations unit(s)1 Tim – Eocene fine-grained mixed clastic & Indian Meadows Formation Indian Meadows Formation Indian Meadows Formation – – Tim – medium-grained mixed clastic rocks Cim Indian Meadows confining unit undefined Tertiary hydrogeologic 2 Tta – Eocene fine-grained mixed clastic & Tatman Formation Tatman Formation – – unit(s) Tta – – – oil shale rocks Twl Twl Eocene fine-grained mixed clastic & Willwood Formation Willwood Formation – Willwood Formation – Twl Twl medium-grained mixed clastic rocks Awl Willwood aquifer Tfu Tfu Paleocene sandstone & shale Fort Union Formation Fort Union Formation Fort Union Formation Fort Union Formation Tfu Tfu Afu Fort Union aquifer Afu Fort Union aquifer TKu – Upper Cretaceous & Paleocene Sedimentary rocks – Sedimentary rocks – TKu – – – undifferentiated Tertiary geologic sandstone & shale unit(s)1 MESOZOIC UNITS Ki – Cretaceous plutonic rocks Intrusive igneous rocks Intrusive igneous rocks – – Ki – – – Klc – Upper Cretaceous sandstone & Landslide Creek Formation Landslide Creek Formation – – Klc – – – undefined Mesozoic hydrogeologic conglomerate unit(s)2 Kha – Upper Cretaceous sandstone & Harebell Formation Harebell Formation – – Kha – – – conglomerate Kl Kl Upper Cretaceous sandstone & shale Lance Formation Lance Formation Lance Formation Lance Formation Kl Kl Ala Lance aquifer Ala Lance aquifer Klm – Upper Cretaceous medium-grained Lewis Shale & Bearpaw Formation Lewis Shale & Bearpaw Formation Lewis Shale & Bearpaw Formation – undifferentiated Mesozoic geologic undifferentiated Mesozoic geologic Klm – mixed clastic & fine-grained mixed – unit(s)1 unit(s)1 clastic rocks Km Km Upper Cretaceous sandstone & Meeteetse Formation Meeteetse Formation Meeteetse Formation Meeteetse Formation Km Amt Km claystones Meeteetse aquifer & confining unit Kml – Upper Cretaceous medium-grained Meeteetse Formation & Lewis – Meeteetse Formation & Lewis – Kml – mixed clastic & fine-grained mixed Shale – Shale – Cml Meeteetse-Lewis confining unit clastic rocks Kle – Upper Cretaceous shale & sandstone Lewis Shale – Lewis Shale – Kle – – – Ket – Upper Cretaceous sandstone & shale Everts Formation, Eagle Everts Formation, Eagle – – Ket – Sandstone, & Telegraph Creek Sandstone, & Telegraph Creek – – Cretaceous Cretaceous units Formation Formation undefined Mesozoic hydrogeologic 2 Kb – Upper Cretaceous sandstone & coal Bacon Ridge Sandstone Bacon Ridge Sandstone – – unit(s) Kb – – – Kmv Kmv Upper Cretaceous sandstone & shale Mesaverde Group Mesaverde Group Mesaverde Group Mesaverde Group Kmv Kmv Amv Mesaverde aquifer Amv Mesaverde aquifer Kc Kc Upper Cretaceous shale & sandstone Cody Shale Cody Shale Cody Shale Cody Shale Kc Kc Cc Cody Shale confining unit Cc Cody Shale confining unit Kf Kf Upper Cretaceous sandstone & shale Frontier Formation Frontier Formation Frontier Formation Frontier Formation Kf Kf Afr Frontier aquifer Afr Frontier aquifer Kft – Upper-Lower Cretaceous sandstone & Frontier Formation, Mowry Shale, Frontier Formation, Mowry Shale, Frontier Formation, Mowry Shale, – Kft – – undifferentiated Mesozoic undifferentiated Mesozoic shale & Thermopolis Shale & Thermopolis Shale & Thermopolis Shale geologic unit(s) 1 geologic unit(s) 1 Kmt Kmt Lower Cretaceous shale & sandstone Mowry Shale, Muddy Sandstone, & Mowry Shale, Muddy Sandstone, & Mowry Shale, Muddy Sandstone, & Mowry Shale, Muddy Sandstone, & Kmt Kmt Ctm Ctm Thermopolis Shale Thermopolis Shale Thermopolis