The Erfurt Formation, also known as the Lower Keuper (

German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ger ...

: ''Untere Keuper'', ''Lettenkeuper'', ''Lettenkohle'' or ''Lettenkohlenkeuper''), is a stratigraphic formation of the

Keuper The Keuper is a lithostratigraphic unit (a sequence of rock strata) in the subsurface of large parts of west and central Europe. The Keuper consists of dolomite, shales or claystones and evaporites that were deposited during the Middle and Late ...

group and the

Germanic Trias The Germanic Trias Supergroup (german: Germanische Trias-Supergruppe) is a lithostratigraphy, lithostratigraphic unit (a sequence of rock strata) in the subsurface of large parts of western and central Europe (north of the Alps) and the North Sea. ...

supergroup. It was deposited during the

Ladinian The Ladinian is a stage and age in the Middle Triassic series or epoch. It spans the time between Ma and ~237 Ma (million years ago). The Ladinian was preceded by the Anisian and succeeded by the Carnian (part of the Upper or Late Triassic). ...

stage of the

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

period.Erfurt Formation
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org It lies above the

Upper Muschelkalk The Muschelkalk (German for "shell-bearing limestone"; french: calcaire coquillier) is a sequence of sedimentary rock strata (a lithostratigraphic unit) in the geology of central and western Europe. It has a Middle Triassic (240 to 230 million yea ...

and below the

Middle Keuper Middle or The Middle may refer to: * Centre (geometry), the point equally distant from the outer limits. Places * Middle (sheading), a subdivision of the Isle of Man * Middle Bay (disambiguation) * Middle Brook (disambiguation) * Middle Creek ...

Definition

The formation was defined in Erfurt-Melchendorf in 1830 by Franz Xaver Hofmann and named for the nearby town of

Erfurt Erfurt () is the capital and largest city in the Central German state of Thuringia. It is located in the wide valley of the Gera river (progression: ), in the southern part of the Thuringian Basin, north of the Thuringian Forest. It sits i ...

. The Erfurt Formation is underlain by the

. 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 Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...

, lacustrine

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

claystone Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone, slate, and shale. Most of the particles of which the stone is composed are less than and are too sm ...

evaporite An evaporite () is a water-soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as ocea ...

s, and fluviatile

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

s. 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. The upper boundary is marked by dolomites, or

s of the Grabfeld Formation.

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 A bone bed is any geological stratum or deposit that contains bones of whatever kind. Inevitably, such deposits are sedimentary in nature. Not a formal term, it tends to be used more to describe especially dense collections such as Lagerstätte. ...

, but in 1977 the first complete skeletons were found near

Kupferzell Kupferzell is a small German town in the district of Hohenlohe in Baden-Württemberg, Germany named after the Kupfer river flowing through it. The largest neighbouring towns are Künzelsau (to the north) and Schwäbisch Hall (to the south). Hi ...

. They include ''

Mastodonsaurus ''Mastodonsaurus'' (meaning "teat tooth lizard") is an extinct genus of temnospondyl amphibian from the Middle Triassic of Europe. It belongs to a Triassic group of temnospondyls called Capitosauria, characterized by their large body size and pre ...

'', '' Gerrothorax'', '' Plagiosuchus'', '' Callistomordax'', '' Nanogomphodon'', ''

Batrachotomus ''Batrachotomus'' is a genus of prehistoric archosaur. Fossils of this animal have been found in southern Germany and dated from the Ladinian stage of the Middle Triassic period, around 242 to 237 million years ago. ''Batrachotomus'' was descr ...

'', '' Kupferzellia'' and '' Palaeoxyris friessi''.

Reptiles

Synapsids

Amphibians

Bony fish

Cartilaginous fish

References

{{Reflist Geologic formations of Germany Triassic System of Europe Triassic Germany Ladinian Stage Marl formations Dolomite formations Limestone formations Shale formations Sandstone formations Shallow marine deposits Ooliferous formations Fossiliferous stratigraphic units of Europe Paleontology in Germany Formations Formations