Erfurt Formation
The Erfurt Formation, also known as the Lower Keuper (German: Untere Keuper, Lettenkeuper, Lettenkohle or Lettenkohlenkeuper), is a stratigraphic formation of the Keuper group and the Germanic Trias supergroup. It was deposited during the Ladinian stage of the Triassic period.[2] It lies above the Upper Muschelkalk and below the Middle Keuper.[1]
| Erfurt Formation Stratigraphic range: Ladinian ~242–237 Ma | |
|---|---|
 Outcrop of the formation in Vellberg | |
| Type | Geological formation |
| Unit of | Lower Keuper |
| Sub-units | Bairdienkalk, Grenzdolomit, Lettenkeuper, Sandige Pflanzenschiefer, Untere Graue Mergel & Werksandstein Members |
| Underlies | Grabfeld Formation |
| Overlies | Upper Muschelkalk |
| Thickness | 20–700 m (66–2,297 ft)[1] |
| Lithology | |
| Primary | Marl |
| Other | Claystone, dolomite, limestone, sandstone |
| Location | |
| Coordinates | 50.949036°N 11.070136°E |
| Approximate paleocoordinates | 15.1°N 16.6°E |
| Region | Baden-Württemberg, Thuringia |
| Country |  Germany |
| Extent | Mittelgebirge, North German Plain |
| Type section | |
| Named for | Erfurt |
| Named by | Hoffmann |
| Year defined | 1830 |
  Erfurt Formation (Germany) | |
Definition
The formation was defined in Erfurt-Melchendorf in 1830 by Franz Xaver Hofmann and named for the nearby town of Erfurt.[1]
The Erfurt Formation is underlain by the Upper Muschelkalk. The lower boundary to the Erfurt Formation is the "Lettenkohlensandstein" in northern Germany and the "Grenz-bone-beds" in southern Germany.
The formation is a sequence of dolomite, lacustrine limestones, claystone, evaporites, and fluviatile sandstones. The color is usually grey but can also be brown or reddish brown. The average thickness is 60 to 80 meter, with a maximum thickness of 700 meter in the Glückstadt-Graben.[1]
The upper boundary is marked by dolomites, or claystones of the Grabfeld Formation.[1]
Fossil content
The Erfurt Formation is known for its vertebrate fossils. Different kinds of fish, amphibians and archosauriforms have been found. Usually they are found as bone beds, but in 1977 the first complete skeletons were found near Kupferzell. They include Mastodonsaurus, Gerrothorax, Plagiosuchus, Callistomordax, Nanogomphodon, Batrachotomus, Kupferzellia and Palaeoxyris friessi.[3]
References
- "Erfurt Formation". BGR. Archived from the original on 10 February 2013. Retrieved 2 March 2013.
- Erfurt Formation at Fossilworks.org
- Ronald Böttcher (2010). "Description of the shark egg capsule Palaeoxyris friessi n. sp. from the Ladinian (Middle Triassic) of SW Germany and discussion of all known egg capsules from the Triassic of the Germanic Basin" (PDF). Palaeodiversity. 3: 123–139. Retrieved 23 January 2012.