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Collier Shale
The Collier Shale is a Formation (geology), geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. Dating from the Late Cambrian to Early Ordovician Period (geology), periods, the Collier Shale is the oldest stratigraphic unit exposed in Arkansas. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas. Purdue assigned the Type locality (geology), type locality to the headwaters of Collier Creek in Montgomery County, Arkansas, Montgomery County, Arkansas, but did not designate a stratotype. As of 2017, a reference section for this unit has yet to be designated. Paleofauna Conodonts * ''Acanthodus'' : ''A. lineatus'' * ''Acodus'' : ''A. oneotensis'' * ''Chosonodina'' : ''C. herfurthi'' * ''Cordylodus'' : ''C. angulatus'' * ''Drepanodus'' : ''D. subarcuatus'' * ''Loxodus'' : ''L. bransoni'' * ''Oistodus'' : ''O. triangularis'' * ''Paltodus'' : ''P. bassleri'' * ''Phakelodus'' : ''P. tenu ... [...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] |
