Muschelkalk (German: shellbearing 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 years) age and forms the
middle part of the tripartite Germanic Trias, that give the Triassic
its name, lying above the older
Buntsandstein and below the younger
Muschelkalk ("mussel chalk") consists of a sequence of
limestone and dolostone beds.
In the past, the time span in which the
Muschelkalk was deposited
could also be called "Muschelkalk". In modern stratigraphy, however,
the name only applies to the stratigraphic unit.
An outcrop of
Muschelkalk cliffs forms the shore of the Wutach River,
in the south of Baden-Württemberg.
Muschelkalk was first used by German geologist Georg
Christian Füchsel (1722-1773). In 1834, Friedrich August von Alberti
included it into the
Triassic system. The name indicates a
characteristic feature of the unit, namely the frequent occurrence of
lenticular banks composed of fossil shells. The
restricted to the subsurface in most of Germany and adjacent regions
as the low countries, the
North Sea and parts of Silesia,
Denmark. Outcrops are found in Thuringia, the Harz, Franconia, Hesse,
Swabia, and the
Saarland and in Alsace.
Muschelkalk was deposited in a land-locked sea which, in the
earlier part of its existence, had only imperfect communications with
the more open waters of the
Tethys Ocean to the south. The basin in
Muschelkalk was deposited is called the Germanic Basin.
Sometimes stratigraphic units with the same age from the Alps,
southern Europe and even
Asia are called
Muschelkalk too. Of course
these rocks have little history in common with the central European
Muschelkalk except for similarities in fossil content. Closer at hand,
Muschelkalk differs in many respects from that of Central
Europe, and in its characteristic fossil fauna has a closer affinity
Triassic Tethys realm.
Muschelkalk can be up to 100 meters thick; it is divisible into
three subdivisions, of which the upper and lower are pale thin-bedded
limestones with greenish-grey marls, the middle group being composed
of gypsiferous and saliniferous marls with dolostone. Stylolites are
common in all the
The lithostratigraphic status of the
Muschelkalk differs regionally.
In Germany it is considered a group, in the
Netherlands a formation.
The top of the hard limestone (Schaumkalk) bed forms the top of the
Wellenkalk or Lower
Muschelkalk and the base of the Orbicularismergel,
part of the Karlstadt-Formation.
Outcrop near Dörzbach,
Encrinus liliiforrnis from the Upper
Kirchberg an der Jagst, Baden-Württemberg. Field of view
Muschelkalk Group is subdivided into three subgroups:
Upper, Middle and Lower Muschelkalk. The Lower
mainly of limestone, calcareous marls and clayey marls. Some beds are
composed of porous cellular limestone, the so-called Schaumkalk, there
are also oolite beds. The Lower
Muschelkalk is divided into six
formations: Jena Formation, Rüdersdorf Formation, Udelfangen
Formation, Freudenstadt Formation and Eschenbach Formation. The Lower
Muschelkalk is sometimes called Wellenkalk, German: Welle the "wave"
chalk, so called on account of the buckled wavy character the bedding
has received. In the
Alsace and northern Eifel, the Lower
Muschelkalk has more sandy beds, the Muschelsandstein., "mussel
Muschelkalk or Anbydnite Group consists mainly of
evaporites (gypsum, anhydrite and halite) and is divided into three
formations: Karlstadt Formation,
Heilbronn Formation and Diemel
Formation. The sedimentary facies at the margins of the Germanic Basin
is different and these deposits are classified as a separate
formation, the Grafenwöhr Formation, which continues into the Upper
Muschelkalk. In the Middle Muschelkalk, weathering can form
characteristic cellular dolostone (Zellendolomit).
Muschelkalk (Hauptmuschelkalk) is similar to the Lower
Muschelkalk and consists of regular beds of shelly limestone, marl and
dolostone. It is divided into six formations: Trochitenkalk, Meißner
Formation, Irrel Formation, Gilsdorf Formation and Warburg Formation.
The lower portion or Trochitenkalk is often composed entirely of the
fragmentary stems of the crinoid
Encrinus liliiformis; higher up come
beds with a series of ammonites,
Ceratites cornpressus, Ceratites
Ceratites semipartitus in ascending order. In
Franconia the highest beds are platy dolomites with Tringonodus
sandergensis and the crustacean Bairdia.
In addition to the fossils mentioned above, the following are
Muschelkalk forms: Terebratulina vulgaris, Spiriferina Mantzeln and S.
hirsute, Myophoria vulgaris, Rhynchotites hirundo,
Ptychites studeri, Balatonites balatonicus, Aspidura scutellate,
Daonella Lommeli, and in the Alpine region several rock-forming Algae,
Baciryllium, Gyroporella, Diptopora, etc.
The salt beds are worked at Hall, Friedrichshall, Heilbronn, Szczecin
and Erfurt. It is from this division that many of the mineral springs
Thuringia and south Germany obtain their saline contents.
This article incorporates text from a publication now in
the public domain: Chisholm, Hugh, ed. (1911). "Muschelkalk".
Encyclopædia Britannica (11th ed.). Cambridge University Press.
^ Gradstein, F.M.; Ogg, J.G.; Smith, A.G. (2005), A Geologic Time
Scale 2004, Cambridge University Press, ISBN 9780521786737