Geologic units in Campbell county, Wyoming

Wasatch Formation (Eocene) at surface, covers 54 % of this area

(Thrust Belt) Main body--Variegated red to gray, brown, and gray mudstone and sandstone; conglomeratic lenses. (in southwest Wyoming) - Drab to variegated claystone and siltstone, carbonaceous shale and coal, buff sandstone, arkose, and conglomerate. In northwestern part of Green River Basin is thick arkosic light-yellowish-tan sandstone intertonguing with pale-green to gray claystone and shale. (in east Wyoming) - Drab sandstone and drab to variegated claystone; numerous coal beds in lower part.

Fort Union Formation - Tongue River Member (Paleocene) at surface, covers 15 % of this area

Thick beds of yellow sandstone interbedded with gray and black shale and many coal beds.

Fort Union Formation - Lebo Member (Paleocene) at surface, covers 9 % of this area

Dark-gray clay shale and concretionary sandstone.

Fort Union Formation - Tullock Member (Paleocene) at surface, covers 9 % of this area

Soft gray sandstone, gray and brown carbonaceous shale, and thin coal beds.

Fort Union Formation - Tongue River and Lebo Members (Paleocene) at surface, covers 7 % of this area

Tongue River (Tftr) - Thick beds of yellow sandstone interbedded with gray and black shale and many coal beds. Lebo Member (Tfl) - Dark-gray clay shale and concretionary sandstone.

Alluvium and Colluvium (Pleistocene-Holocene) at surface, covers 3 % of this area

Clay, silt, sand, and gravel in flood plains, fans, terraces, and slopes.

Fort Union Formation - Lebo and Tullock Members (Paleocene) at surface, covers 1 % of this area

Lebo Member (Tfl) - Dark-gray clay shale and concretionary sandstone. Tullock Member (Tft) - Soft gray sandstone, gray and brown carbonaceous shale, and thin coal beds.

Lance Formation (Upper Cretaceous) at surface, covers 0.9 % of this area

(North Wyoming) - Thick-bedded buff sandstone and drab to green shale; thin conglomerate lenses. (South and Northeast Wyoming) - Brown and gray sandstone and shale; thin coal and carbonaceous shale beds.

Pierre Shale (Upper Cretaceous) at surface, covers 0.2 % of this area

Dark-gray concretionary marine shale; contains several bentonite beds.

Fox Hills Sandstone (Upper Cretaceous) at surface, covers 0.2 % of this area

Light-colored sandstone and gray sandy shale containing marine fossils.

Tongue River Member of Fort Union Formation (Tertiary) at surface, covers < 0.1 % of this area

Yellowish orange sandstone, sandy and silty carbonaceous shale, and coal. Alluvial plain. Thickness as much as 300 m (984 ft).

White River Formation (Oligocene) at surface, covers < 0.1 % of this area

White to pale-pink blocky tuffaceous claystone and lenticular arkosic conglomerate.

Tullock Member of Fort Union Formation (Tertiary) at surface, covers < 0.1 % of this area

Yellow sandstone interbedded with subordinate grayish brown and black shale and thin beds of coal. Alluvial plain. Thickness as much as 180 m (590 ft).

Alluvium (Quaternary) at surface, covers < 0.1 % of this area

Gravel, sand, silt, and clay deposits of stream and river channels, and floodplains.

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

Light gray, bentonitic claystone that alternates with gray to brown sandstone interbedded with carbonaceous shale. Laterally equivalent to Lance Formation. Fluvial and flood plain. Thickness as much as 335 m (1,100 ft).

Lebo Member of Fort Union Formation (Tertiary) at surface, covers < 0.1 % of this area

Dark gray carbonaceous shale, bentonitic claystone, sandstone, and coal. Alluvial plain. Thickness as much as 185 m (607 ft).