Geologic units in Millard county, Utah

Alluvium and colluvium (Quaternary) at surface, covers 49 % of this area

Alluvium and colluvium

Lake Bonneville deposits (Quaternary) at surface, covers 17 % of this area

Lake Bonneville deposits

Basalts (Quaternary) at surface, covers 4 % of this area

Basalts

Pilot Shale, Guilmette Formation, and Simonson and Sevy Dolomites (Devonian to Mississippian) at surface, covers 3 % of this area

Pilot Shale, Guilmette Formation, and Simonson and Sevy Dolomites.

Notch Peak, Orr, Lamb, Weeks, and Wah Wah Summit Formations (Middle Cambrian to Early Ordovician) at surface, covers 2 % of this area

Notch Peak, Orr, Lamb, Weeks, and Wah Wah Summit Formations.

Playa (Holocene) at surface, covers 2 % of this area

Playa

Trippe Ls, Marjum/Pierson Cove Fms, Wheeler Shale, Swasey Ls, Whirlwind Fm, Dome Ls, Chisholm Fm, Howell Fm, and Pioche Fm (Middle Cambrian) at surface, covers 2 % of this area

Trippe Ls, Marjum/Pierson Cove Fms, Wheeler Shale, Swasey Ls, Whirlwind Fm, Dome Ls, Chisholm Fm, Howell Fm, and Pioche Fm.

Ely Springs Dm, Eureka Qtz, Crystal Peak Dm, Watson Ranch Qzt, and the Pogonip Group (Ordovician) at surface, covers 2 % of this area

Ely Springs Dm, Eureka Qtz, Crystal Peak Dm, Watson Ranch Qzt, and the Pogonip Group (Lehman Formation, Kanosh Shale, Juab, Wah Wah, Fillmore, and House Limestones).

Arcturus Formation (Early Permian) at surface, covers 1 % of this area

Arcturus Formation.

Isom Fm, Needles Range Fm, Escalante Desert Fm, Sawtooth Peak Fm, and Tunnel Springs Tuff (Late Eocene to Oligocene) at surface, covers 1 % of this area

Isom Fm (tuff), Needles Range Fm (ash-flow tuff), Escalante Desert Fm (ash-flow tuff), Sawtooth Peak Fm (ash-flow tuff), and Tunnel Springs Tuff.

Oquirrh Group (Pennsylvanian to Permian) at surface, covers 1 % of this area

Oquirrh Group (10,000+ feet thick) of Cedar Mountains and vicinity, is equivalent, in part to Arcturus Formation and Ely Limestone elsewhere

North Horn Formation (Late Cretaceous to Eocene) at surface, covers 1 % of this area

North Horn Formation.

Prospect Mountain Quartzite (Early Cambrian) at surface, covers 1 % of this area

Prospect Mountain Quartzite (3,500 feet thick).

Salt Lake Formation (?) and other Basin & Range valley-filling alluvial, lacustrine, and volcanic materials (Middle Miocene to Late Pliocene) at surface, covers 1.0 % of this area

Salt Lake Formation (?) and other Basin & Range valley-filling alluvial, lacustrine, and volcanic materials. Valley fill is more than 13,000 feet thick in the central part of Utah Valley.

Tintic Quartzite (Early to Middle Cambrian) at surface, covers 0.8 % of this area

Tintic Quartzite.

Laketown Dolomite (Silurian) at surface, covers 0.8 % of this area

Laketown Dolomite.

Navajo/Nugget Sandstone (Early Jurassic) at surface, covers 0.7 % of this area

Navajo/Nugget Sandstone.

Gerster Limestone, Plympton Formation and Kaibab Limestone (Permian) at surface, covers 0.7 % of this area

Gerster Limestone, Plympton Formation and Kaibab Limestone.

Eolian deposits (Quaternary) at surface, covers 0.6 % of this area

Eolian deposits

Marshes (Holocene) at surface, covers 0.6 % of this area

Marshes

Salt Lake Formation and other Basin & Range valley-filling alluvial, lacustrine, and volcanic materials (Middle Miocene to Late Pliocene) at surface, covers 0.5 % of this area

Salt Lake Formation and other Basin & Range valley-filling alluvial, lacustrine, and volcanic materials. Valley fill is more than 8,000 feet thick in places and includes salt masses under the Sevier Desert.

Precambrian rocks of the Canyon Range (Proterozoic Z) at surface, covers 0.5 % of this area

Precambrian rocks of the Canyon Range (Mutual Fm, Inkom Fm, Caddy Canyon Qtz, Papoose Creek Fm, Blackrock Canyon Ls, and upper part of Pocatello Fm).

Maxfield Limestone and Ophir Formation (Middle Cambrian) at surface, covers 0.5 % of this area

Maxfield Limestone (Opex Fm, Cole Canyon Dm, Bluebird Dm, Herkimer Ls, Dagmar Dm, and Teutonic Ls) and Ophir Formation.

Miocene volcanic rocks, undivided (Late Oligocene to Middle Miocene) at surface, covers 0.5 % of this area

In Western Utah: Quichapa Group and other volcanic rocks (Tmb,Tmr,Tma). In Central Utah: Silver Shield Latite (17 my) and Pinyon Creek Conglomerate.

Joana Limestone (Mississippian) at surface, covers 0.4 % of this area

Joana Limestone.

Ochre Mountain Limestone and Woodman Formation (Mississippian) at surface, covers 0.4 % of this area

Ochre Mountain Limestone (Great Blue equivalent) and Woodman Formation (Deseret Humbug equivalent).

Flagstaff Limestone (Late Paleocene to Early Eocene) at surface, covers 0.4 % of this area

Flagstaff Limestone.

Rhyolites (Quaternary) at surface, covers 0.4 % of this area

Rhyolites

McCoy Creek and Sheeprock Groups (Precambrian) at surface, covers 0.3 % of this area

McCoy Creek and Sheeprock Groups (10,000+ feet thick).

Ajax Dolomite and Opex Formation (Middle Cambrian to Early Ordovician) at surface, covers 0.3 % of this area

Ajax Dolomite and Opex Formation (upper member of Maxfield Limestone).

Price River Formation (Late Cretaceous) at surface, covers 0.3 % of this area

Price River Formation.

Older alluvial deposits (Quaternary) at surface, covers 0.2 % of this area

Older alluvial deposits

Iron Springs Formation of Cedar City Area (Kaiparowits Fm) (Late Cretaceous) at surface, covers 0.2 % of this area

Iron Springs Formation of Cedar City Area (Kaiparowits Fm).

Tertiary volcanic rocks, undivided (Tertiary) at surface, covers 0.2 % of this area

Tertiary volcanic rocks, undivided.

Fish Haven Dolomite and Opohonga Limestone (Ordovician) at surface, covers 0.1 % of this area

Fish Haven Dolomite and Opohonga Limestone.

Kaibab Limestone and Toroweap Formation (Early Permian) at surface, covers 0.1 % of this area

Kaibab Limestone and Toroweap Formation.

Granitic rocks (140 my) in House Range and near Wendover (Jurassic) at surface, covers 0.1 % of this area

Granitic rocks (140 my) in House Range and near Wendover.

Moenkopi Formation (Early Triassic) at surface, covers 0.1 % of this area

Moenkopi Formation.

Callville Limestone (Pennsylvanian) at surface, covers 0.1 % of this area

Callville Limestone.

Basalts (Early to Middle Miocene) at surface, covers < 0.1 % of this area

In Southwestern Utah: In Cedar City area: Page Ranch Fm, Rencher Fm and Quichapa Group (24my). In Marysvale area: Joe Lott Tuff, Mt. Belknap Volcanics, Osiris Tuff and Mt. Dutton Formation.

Moenkopi and Thaynes Formations (Early Triassic) at surface, covers < 0.1 % of this area

Moenkopi (in Blue Mountain) and Thaynes (north of Confusion Range) Formations.

Bluebell Dolomite (Late Ordovician to Silurian) at surface, covers < 0.1 % of this area

Bluebell Dolomite.

Indianola Formation (Cretaceous) at surface, covers < 0.1 % of this area

Indianola Formation.

Sevier River Formation (Miocene to Pliocene) at surface, covers < 0.1 % of this area

Sevier River Formation.

Coconino Sandstone, Supai Group, and Pakoon Formation (Early Permian) at surface, covers < 0.1 % of this area

Coconino Sandstone, Supai Group, and Pakoon Formation.

Pinyon Peak Limestone and Victoria Formation (Devonian) at surface, covers < 0.1 % of this area

Pinyon Peak Limestone and Victoria Formation.

Rhyolites (Middle to Late Miocene) at surface, covers < 0.1 % of this area

In Northwestern Utah: Dacitic tuff (8.5 my). In Logan-Huntsville Allochthon: rhyolite.

Redwall Limestone (Mississippian) at surface, covers < 0.1 % of this area

Redwall Limestone (chert).

Alluvium, undifferentiated (Holocene and Pleistocene) at surface, covers < 0.1 % of this area

Unit is present in all counties. Some counties divided the alluvium into younger and older units, and some did not. For those that did not, or used other generalized terms for Quaternary rocks, the unit Qal has been used for the general undivided alluvium. Additionally, when polygons have been edited and changed to alluvium, Qal was used as the general value; hence it now is present in all counties. Qya-Younger alluvium: Map unit is used in Churchill, Elko, Esmeralda, Eureka, Humboldt, Lander, and Lincoln Counties where geologic information suggests better-defined younger versus older alluvium. It is mostly interchangeable with Qal, except that it implies some specifically younger Quaternary deposits.

Alluvial materials, Axtell and Harkers Formations (Pliocene to Quaternary) at surface, covers < 0.1 % of this area

Alluvial materials, Axtell and Harkers Formations

Quartz Monzonite and granite (Oligocene to Miocene) at surface, covers < 0.1 % of this area

Quartz Monzonite (in Cedar City area) and monzonite and granite (in Marysvale area).

Chinle Formation and Shinarump Conglomerate Member (Late Triassic) at surface, covers < 0.1 % of this area

Chinle Formation and Shinarump Conglomerate Member.

Thaynes Formation and Woodside Shale (Early Triassic) at surface, covers < 0.1 % of this area

Thaynes Formation and Woodside Shale.

Duchesne River, Uinta and Bridger Formations (Late Eocene to Early Oligocene) at surface, covers < 0.1 % of this area

Duchesne River, Uinta and Bridger Formations

Green River Formation (Eocene) at surface, covers < 0.1 % of this area

Green River Formation.

Isom Fm, Needles Range Fm, and Bullion Canyon Volcanics (Late Eocene to Oligocene) at surface, covers < 0.1 % of this area

In Cedar City area: Isom Fm and Needles Range Fm (29 my). In Marysvale area: Bullion Canyon Volcanics.

Park City and Phosphoria Formations (Permian) at surface, covers < 0.1 % of this area

Park City and Phosphoria Formations.

Ankareh Shale (Middle to Late Triassic) at surface, covers < 0.1 % of this area

Ankareh Shale.

Mud and salt flats (Holocene) at surface, covers < 0.1 % of this area

Mud and salt flats

Metamorphic rocks (Precambrian) at surface, covers < 0.1 % of this area

Metamorphic rocks.

Silver City Monzonite, Sunrise Peak Monzonite Porphyry, Swanson Quartz Monzonite (Late Eocene to Oligocene) at surface, covers < 0.1 % of this area

Silver City Monzonite (31 my), Sunrise Peak Monzonite Porphyry, Swanson Quartz Monzonite

Basalts (Pliocene) at surface, covers < 0.1 % of this area

Basalts