Rottenstone (Vanport Flint, Middle Pennsylvanian; Nethers Flint Quarries, Flint Ridge, Ohio, USA) 2 : 無料・フリー素材/写真
Rottenstone (Vanport Flint, Middle Pennsylvanian; Nethers Flint Quarries, Flint Ridge, 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 | Rottenstone from the Pennsylvanian of Ohio, USA.This ugly specimen is a scarce, distinctive rock type called rottenstone, also called tripoli. The dark brown, closely-spaced, rounded to subrounded masses are not sediment grains - they are weathering spherulites. Rottenstone forms by extreme, long-term weathering. This sample is rottenstone after chert (flint) from Flint Ridge, Ohio. In this area, the Middle Pennsylvanian-aged Vanport Flint is exposed in several places. The geologic literature on the Vanport Flint is relatively sparse, with inaccurate, incomplete descriptions and characterizations. For example, the literature describes the Vanport as a sheet of flint at Flint Ridge - it's actually a meganodule horizon. Other descriptions refer to the chert as the remains of siliceous sponges. In reality, siliceous sponge spicules are quite scarce in Vanport samples.Many of the weathering spherulites here resemble oolites (= sand-sized, subspherical, well-rounded, concentrically layered, calcium carbonate grains that form by back-and-forth rolling from wave action in shallow water), but have a very different origin.Stratigraphy: Vanport Flint, Allegheny Group, upper Middle PennsylvanianLocality: Nethers Flint Quarries - flint pit in the woods on the southwestern side of Flint Ridge Road, eastern Flint Ridge, far-western Muskingum County, east-central Ohio, USA (vicinity of 40° 00.137’ North latitude, 82° 11.544’ West longitude) |
| 撮影日 | 2025-05-01 14:13:56 |
| 撮影者 | James St. John |
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