Stromatolite (Salina Group, Upper Silurian; Duff Quarry, near Huntsville, Ohio, USA) 2 : 無料・フリー素材/写真
Stromatolite (Salina Group, Upper Silurian; Duff Quarry, near Huntsville, 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 | Stromatolite from the Silurian of Ohio, USA. (cross-section view; cut surface)Stromatolites are macroscopic layered structures built up by mats of cyanobacteria. They vary in appearance, ranging from slightly wrinkled horizontal laminations in sedimentary rocks to low mounds to prominent mounds to columnar structures and other forms. Stromatolites are most common in the Proterozoic fossil record. They are scarce today, but famous modern examples occur at Shark Bay, Western Australia. The oldest known examples are ~3.5 billion years old, from Western Australia.This stromatolite comes from Duff Quarry in western Ohio. The quarry has exposures of Silurian bedded dolostones over massive dolostones. Stromatolites and mudcracks are present, indicating shallow water to subaerial conditions. Conodont microfossils from this locality indicate a mid-Late Silurian age (= late Ludlovian to early Pridolian) (see Swift, 2011). Stratigraphy: Salina Group, upper Ludlovian Series to lower Pridolian Series, mid-Upper Silurian Locality: Duff Quarry, north of the town of Huntsville, northern Logan County, western Ohio, USA (40° 28' 38.79" North latitude, 83° 48' 15.59" West longitude)-----------------Reference cited:Swift (2011) - Conodont Biostratigraphy and δ13C Chemostratigraphy of the Salina Group (Silurian) in Western Ohio and Eastern Indiana. Master's thesis. Ohio State University, Columbus, Ohio, USA. 91 pp. [etd.ohiolink.edu/acprod/odb_etd/etd/r/1501/10?clear=10&am...]------------------------Info. at:en.wikipedia.org/wiki/Stromatolite |
| 撮影日 | 2025-06-02 17:01:04 |
| 撮影者 | James St. John |
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