Columbus Limestone (Middle Devonian; Wright Run Creek, Dublin, Ohio, USA) 2 : 無料・フリー素材/写真
Columbus Limestone (Middle Devonian; Wright Run Creek, Dublin, Ohio, USA) 2 / 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 | Limestone in the Devonian of Ohio, USA.The Columbus Limestone is a significant carbonate unit in the Devonian of central and northern Ohio. It's actually part of a much more widespread sheet of Devonian carbonates that extends from New York State to the Midwest. The Columbus Limestone represents deposition in a subtropical, shallow-water, carbonate platform environment. The rocks are principally micritic limestones, fossiliferous wackestones, and fossiliferous packstones. Some chert nodules are present in the unit. Fossils are typical Paleozoic shallow marine invertebrates - favositid corals, rugose corals, stromatoporoids brachiopods, crinoids, blastoids, bryozoans, trilobites, bivalves, gastropods, cephalopods, rostroconchs, and tentaculites. Microfossils include conodonts and charophyte oogonia. Other fossils in the Columbus Limestone include vertebrates (fish), land plants (rare), and trace fossils. Some fossil horizons in the Columbus Limestone are partially silicified.The thick-bedded Columbus Limestone is overlain by the thin-bedded Delaware Limestone. The contact is a prominent disconformity (a type II sequence boundary). Biostratigraphic studies have shown that one conodont biozone is missing at the Columbus-Delaware contact in central Ohio, probably representing ~1 to 3 million years. The base of the Columbus Limestone is a major, continent-wide unconformity representing the Tippecanoe-Kaskaskia megasequence boundary (a type I sequence boundary).The straight edges along the stream outcrop seen here are joints - fractures in rocks along which there has been no differential displacement. If offset has occurred, such fractures are called faults. Two joint orientations are present - these are conjugate joints.Stratigraphy: Columbus Limestone, Eifelian Stage, lower Middle DevonianLocality: Wright Run Creek, Ferris-Wright Park, Dublin, northwestern Franklin County, Ohio, USA (vicinity of 40° 06’ 42.25” North latitude, 83° 06’ 24.87” West longitude) |
| 撮影日 | 2018-12-19 12:30:54 |
| 撮影者 | James St. John |
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