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 A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

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 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. Almost all of t ...

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, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cre ...

.org It lies above the Upper Muschelkalk and below the Middle Keuper.

Definition

The formation was defined in Erfurt-Melchendorf in 1830 by

Franz Xaver Hofmann Franz may refer to: People * Franz (given name) * Franz (surname) Places * Franz (crater), a lunar crater * Franz, Ontario, a railway junction and unorganized town in Canada * Franz Lake, in the state of Washington, United States – see Fran ...

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 ...

. 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

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 wh ...

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 oce ...

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 The Grabfeld is a region in Germany, on the border between Bavaria and Thuringia. It is situated southeast of the Rhön Mountains. Its highest elevation is 679 metres high in the little Gleichberge mountain range. The Grabfeld gave its name t ...

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. They include '' Mastodonsaurus'', '' 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, Ladinian stage of the Middle Triassic Geological period, period, around 242 to 237 million years ago. ...

'', ''

Kupferzellia ''Kupferzellia'' is an extinct genus of Triassic capitosauroid temnospondyl amphibian Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lis ...

'' 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