| Three Forks Shale Stratigraphic range: Devonian | |
|---|---|
| Type | Formation |
| Location | |
| Region | Montana |
| Country | United States |
The Three Forks Shale is a geologic formation in Montana and North Dakota. It preserves fossils dating back to the Devonian period. [1]
The Eagle Sandstone, originally the Eagle Formation, is a geological formation in Montana whose strata date back to the Late Cretaceous. It is a light to brownish gray to pale yellow-orange, fine-grained sandstone. It contains areas of crossbedding and local shale members. It contains large sandy calcareous concretions. Its thickness varies from 100 to 350 feet due to the lens nature of the individual sandstone layers and local interbedded sandy shale layers.
The Montana Group is a geologic group in South Dakota. It preserves fossils dating back to the Cretaceous period.
The Meagher Formation is a geologic formation in Montana made up of limestone. It preserves fossils dating back to the Cambrian period.
The Snowy Range Formation is a geologic formation in Montana. It preserves fossils dating back to the Cambrian period.
The Wolsey Shale is a geologic formation in Montana. It preserves fossils dating back to the Cambrian period.
The Amsden Formation is a geologic formation in Montana. It preserves fossils dating back to the Carboniferous period.
The Cameron Creek Formation is a geologic formation in Montana. It preserves fossils dating back to the Carboniferous period.
The Lodgepole Limestone is a geologic formation in Montana. It preserves fossils dating back to the Carboniferous period.
The Benton Shale is a geologic formation in Montana, Wyoming, North Dakota, South Dakota, Colorado, Kansas, and Nebraska. It preserves fossils dating to the Cretaceous Period. The term Benton Limestone has also been used to refer to the chalky portions of the strata, especially the upper beds of the strata presently classified as Greenhorn Limestone. The Benton classification is obsolete in some regions, having been replaced by the ascending sequence Graneros Shale, Greenhorn Limestone, and Carlile Shale.
The Marias River Shale is a geologic formation in Montana. It preserves fossils dating back to the Cretaceous period.
The Shell Creek Shale is a geologic formation in Montana. It preserves fossils dating back to the Cretaceous period.
The Jefferson Formation is a geologic formation in Montana. It preserves fossils dating back to the Devonian period.
The Deep River Formation is a geologic formation in Montana. It preserves fossils dating back to the Neogene period.
The Passamari Formation is a geologic formation in Montana. It preserves fossils dating back to the Paleogene period.
The Renova Formation is a geologic formation in Montana. It preserves fossils dating back to the Paleogene period.
The Tullock Formation is a geologic formation in Montana. It preserves fossils dating back to the Paleogene period.
The Park City Formation is a geologic formation in Montana and Utah. It preserves fossils dating back to the Permian period.
The Dinwoody Formation is a geologic formation in Montana. It preserves fossils dating back to the Triassic period.
The Thaynes Formation is a geologic formation in Montana and Idaho. It preserves fossils dating back to the Triassic period, such as Ammonoidea, Actinopterygii, Actinistia, Conodonta, Gastropoda, Nautiloidea, Ichthyosauria and others. A diverse fauna known as the Paris Biota has been described from the Thaynes Formation.
The Belle Fourche Formation or Belle Fourche Shale is a fossiliferous early Late-Cretaceous geologic formation classification in Wyoming. Named for outcrops in Belle Fourche River, Wyoming, this unit name is also used in Montana, North Dakota, and South Dakota.
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