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Composed mostly by black shale, the formation is a Lagerstätte, where fossils show exceptional preservation (Including exquisite soft tissues), with a thickness that varies from about 1 m to about 40 m on the Rhine level, being on the main quarry at Holzmaden between 5 and 14 m. [1]
The Posidonia Shale (German: Posidonienschiefer, also called Schistes Bitumineux in Luxembourg) geologically known as the Sachrang Formation, is an Early Jurassic (Early to Late Toarcian) geological formation in Germany, northern Switzerland, northwestern Austria, southern Luxembourg and the Netherlands, including exceptionally well-preserved complete skeletons of fossil marine fish and reptiles.
It is known from a single, 11 mm long specimen found in black shale. [1] [2] The body shows the presence of a notochord-like structrure running along the length of the body, along with gill slits, along with several unpaired fins, including a tail (caudal) fin with rays that is round and small, a pronounced pelvic fin and a humped dorsal fin ...
The Middlesex is a laminated, dark grey to black formation comprising mudstone and siltstone. It developed in an anoxic environment. Further evidence of this is the lack of bioturbation. There are also sparse sand and silt layers, suggesting that they were single event deposits. [2] Earth sciences portal; New York (state) portal; Paleontology ...
For example, concretions in sandstones or shales are commonly formed of a carbonate mineral such as calcite; those in limestones are commonly an amorphous or microcrystalline form of silica such as chert, flint, or jasper; while those in black shale may be composed of pyrite. [18]
A typical shale is composed of about 58% clay minerals, 28% quartz, 6% feldspar, 5% carbonate minerals, and 2% iron oxides. [8] Most of the quartz is detrital (part of the original sediments that formed the shale) rather than authigenic (crystallized within the shale after deposition). [9]
The Burket Shale or Geneseo Shale is the lowest member of the Harrell Shale/Genessee Group. The Burket is an organic-rich black shale that rests just above the Tully Limestone member of the Mahantango Formation. The geographical extent of the formation includes southern New York, Pennsylvania, eastern Ohio, and West Virginia. The Burket is also ...
These concretions occur in the black shale in the lower part of the Kettle Point Formation. Because the concretions are so much harder than the enclosing weakly indurated shale, they readily weather out of the shale along the shoreline and are incorporated into the rubble mantling the lake bottom adjacent to the outcrop. [3] [5]