Mineral Resources On-Line Spatial Data
Mineral Resources > Online Spatial Data > Geology > by state > Nebraska Geology
Geologic units in Cedar county, Nebraska
- Pierre Shale (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 12 % of this area
Mostly medium to dark-gray, brownish-gray, and black, fissle clay shale. Locally grades to thin beds of calcareous, silty shale or claystone, marl, shaly sandstone, and sandy shale. Locally contains thin seams of gypsum and sparse selenite crystals. Approx. max thickness 1970 ft.
- Outwash, Terrace (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers < 0.1 % of this area
Heterogeneous clay to gravel of glaciofluvial orgin. Thickness up to 60 ft (18m)
- Niobrara Formation (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 50 % of this area
Argillaceous chalk, limestone and shale. Chalk is medium gray to white, interbedded with thin layers of chalky shale; contains many fossil clams, oysters, and formanifera. Limestone is light gray to medium gray and yellowish gray, interbedded with medium-gray chalky shale; also contains fossil clams, oysters, and formanifera. Bedding plans commonly marked by thin layers of gypsum and locally a thin bed of red flint occurs at top of unit. Approx. max thickness 570 ft.
- Dam (None) at surface, covers < 0.1 % of this area
- Carlile Shale (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 7 % of this area
Shale, limestone, and sandstone. At top, locally 5 feet of gray to pale-yellowish brown siltstone or very fine grained sandstone. Upper 200 feet of shale is drak gray to medium gray; locally contains ironstone concretions, and interbedded with thin siltstone. Lower 80 feet of shale is medium gray, calcareous, and contains many very thin bedded, fossiliferous, shaly limestone and calcareous shale layers. Approx. max thickness 300 ft.
- Ogallala Group or Formation (Phanerozoic | Cenozoic | Tertiary | Miocene) at surface, covers 31 % of this area
Silt, sand, sandstone, gravel and conglomerate. Predominantly interfingered fine- to coarse grained, poorly sorted, arkosic, fluvial deposits of light-gray, light-olive-gray, and grayish-green calcareous silt and sand, and locally poorly consolidated conglomerate, sandstone, and siltstone.
- Alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers 0.2 % of this area
Clay to boulder-size clasts with locally abundant organic material. Thickness up to 75 ft (23m).
- Dakota Group (Phanerozoic | Mesozoic | Cretaceous-Early) at surface, covers < 0.1 % of this area
Upper part is white, light-gray, brownish-gray, yellow, redish-brown, and red sandstone and shale. Sandstone is very fine to coarse grained, friable, micaeous, crossbedded, and lenticular; locally contains gravel near base. contains numerous zones of ironstone and siltstone concretions of variable thickness. Middle part is light-gray, yellow, red brown and dark-gray, sandy carbonaceous shale; commonly contains a zone of concretions near top. Lower part is sandstone similar to that in upper except there are zones of siderite concretions and, locally a basal zone of chert pebbles. Approx. max thickness 600 ft.
- Greenhorn Limestone and Graneros Shale (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 0.2 % of this area
Greenhorn Limestone- medium- to light-gray limestone interbedded with argillaceous limestone, marl and calcareous shale; contains Inoceramus fossils. Upper and lower contacts gradational. Approx. max thickness 30 ft. Graneros Shale- medium- to dark-gray, partly calcareous shale. Interbeds of siltstone, sandstone, and carbonaceous shale, and thin bentonite layers in upper part. Approx. max thickness 60 ft.