Natural arch developed in chalk & impure chalk (Smoky Hill Chalk Member, Niobrara Formation, Upper Cretaceous; Monument Rocks, Kansas, USA) 25 : 無料・フリー素材/写真
Natural arch developed in chalk & impure chalk (Smoky Hill Chalk Member, Niobrara Formation, Upper Cretaceous; Monument Rocks, Kansas, USA) 25 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Natural arch developed in chalk & impure chalk in the Cretaceous of Kansas, USA.This western Kansas landscape consists of chalk badlands and chalk pillars and a natural arch. The rocks are chalks and impure chalks (e.g., argillaceous chalk and chalky shale) that range in color from whitish to light gray to yellowish. Chalk is a biogenic, calcitic, marine sedimentary rock composed of numerous coccolith microfossils (see: www.soes.soton.ac.uk/staff/tt/eh/pics/lith2.gif). Coccoliths are individual calcareous plates that covered a single-celled photosynthetic marine organism called a coccolithophorid (a.k.a. coccolithophore) (see: upload.wikimedia.org/wikipedia/commons/d/d9/Emiliania_hux...). These beds were deposited in the ancient Western Interior Seaway, a section of ocean that existed during parts of the Mesozoic Era in what is now the American and Canadian Great Plains.Rock arches are rare erosional features - those developed in chalk beds are even rarer. If a stream goes under an arch, it is known as a natural bridge. If no stream is present, the feature is a natural arch. Along lakeshores, they are called lake arches. Along oceanic coastlines, they are called sea arches. The highest concentration of natural arches on Earth is Arches National Park in eastern Utah.Stratigraphy: Smoky Hill Chalk Member (a.k.a. Smoky Hills Member), Niobrara Formation, mid-Upper CretaceousLocality: Monument Rocks (also known as the Chalk Pyramids), along Gove County Road 16, north of the Smoky Hill River, Gove County, western Kansas, USA (38° 47' 43.24" North latitude, 100° 45' 52.06" West longitude) |
| 撮影日 | 2014-05-19 13:41:53 |
| 撮影者 | James St. John |
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