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Alajuela Formation
The Alajuela Formation, originally Alhajuela Formation (Tau),Geologic Map, 1980 is a Miocene, Late Miocene (Tortonian, Hemphillian, Early Hemphillian or Clarendonian, Latest Clarendonian in the North American land mammal age, NALMA classification) Formation (geology), geologic formation in the Panama Canal Zone of central Panama. The formation overlies the Caimito Formation and comprises sandstones, limestones and conglomerate (geology), conglomerates deposited in a tidal-dominated estuary, estuarine to shallow marine depositional environment, environment. The formation crops out in a small area along the southern and western shores of Lake Alajuela, of which it derives its name, and preserves a rich fossil faunal assemblage of mammals, fish (among which fossil teeth of megalodon), invertebrates and flora. The fauna is of paleontological significance as an insight into the ecosystem of Central America preceding the Great American Biotic Interchange (GABI). Description The Alaj ... [...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] |
