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Imo Formation
The Imo Formation, or Imo Shale, is a geologic unit in northern Arkansas that dates to the Chesterian, Chesterian Series of the late Mississippian (geology), Mississippian. The Imo is considered to be a Stratigraphic unit#Member, member of the upper Pitkin Formation, and is the most recent Mississippian age rock in Arkansas. The Imo Shale unconformably underlies the Pennsylvanian age Hale Formation The stratigraphic placement of this interval has long been debated. It was introduced in 1964 as the "Imo Formation," representing an interval of shale that was presumably of Mississippian and possibly of Pennsylvanian (geology), Pennsylvanian age. However, in a footnote in the first publication to use this designation, the author noted that the shale interval had been mapped into the Pennsylvanian Cane Hill Member of the Hale Formation and revoked use of the name "Imo Formation". The name was reintroduced in 1973 as the "Imo Shale", and in 2010 was classified as a member (geology), me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formation (stratigraphy)
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness (geology), thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
