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West Falls Formation
Description Stratigraphy The West Falls Group is a geologic group in New York. It preserves fossils dating back to the Devonian period. The West Falls formation is bounded above by the Java Formation and below by the Sonyea Formation. It comprises the Angola Shale and Rhinestreet Shale Members. It was deposited during the Acadian Orogeny and is part of the Salina thrust sheet. Geographic distribution The Rhinestreet Shale and Angola Shale Members of the West Falls Formation are both recognized in the subsurface from western New York to eastern Tennessee. Lithology The predominant lithology of the West Falls Group is shale. The Rhinestreet Member can be further subdivided into two shale types: a thick, fissile black shale underlies a gray to greenish-gray shale that likely indicates a transitional environment. The Angola member is a gray to greenish-gray shale, easily distinguished by its consistent low gamma ray signature, which is typical of this shale type. Paleontology ... [...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] |
