Muschelkalk
2849129
164041543
2007-10-12T13:36:59Z
Robinstocks
23137
Corrected 'German for "mussel chalk"' to 'German for "shell limestone"'. "Muschel-" refers to shells, not just mussels, and "Kalk" means limestone, not chalk (the German word for which is "Kreide").
'''Muschelkalk''' ([[German language|German]] for "shell limestone") is the term in [[geology]] for the middle member of the [[Germany|German]] [[Triassic]]. It consists of a series of [[Calcite|calcareous]], many and [[Dolomite|dolomitic]] beds which lie conformably between the [[Buntsandstein]] and [[Keuper]] formations.
The name Muschelkalk (Fr., calcaire coquillier; concijylien, formation of D'Orbigny) indicates a characteristic feature in this series, viz, the frequent occurrence of lenticular banks composed of [[fossil]] shells, remarkable in the midst of a singularly barren group. In its typical form the Muschelkalk is practically restricted to the German region and its immediate neighborhood; it is found in [[Thuringia]], [[Harz]], [[Franconia]], [[Hesse]], [[Swabia]], and the [[Saarland|Saar]] and [[Alsace]] districts. Northward it extends into [[Silesia]], [[Poland]] and [[Heligoland]]. Representatives are found in the [[Alps]], west and south of the [[Vosges]], in [[Moravia]], near [[Toulon]] and [[Montpellier]], in [[Spain]] and [[Sardinia]]; in [[Romania]], [[Bosnia and Herzegovina|Bosnia]], [[Dalmatia]], and beyond this into [[Asia]] in the [[Himalayas]], [[China]], [[Australia]], [[California]], and in [[North Africa]] (Constantine). From the nature of the deposits, as well as from the impoverished fauna, the Muschelkalk of the type area was probably laid down within a land-locked sea which, in the earlier portion of its existence, had only imperfect communications with the more open waters of the period. The more remote representatives of the formation were of course deposited in diverse conditions, and are only to be correlated through the presence of some of the Muschelkalk fossils.
In the German area the Muschelkalk is from 250-350 ft. thick; it is readily divisible into three groups, of which the upper and lower are pale thin-bedded [[limestone]]s with greenish-grey mans, the middle group being composed of [[Gypsum|gypsiferous]] and saliniferous mans with dolomite. The Lower Muschelkalk consists, from below upwards, of the following rocks, the ochreous Wellen Dolomit, lower Wellen Kalk, upper Wellen Kalk (so called on account of the wavy character of the bedding) with beds of Schaumkalk (a porous cellular limestone), and [[Oolite]] and the Orbicularis beds (with ''Myophoria orbicularis''). In the Saar and Alsace districts and north [[Eifel]], these beds take on a sandy aspect, the Muschelsandstein. The Middle Muschelkalk or Anbydnite group, as already indicated, consists mainly of mans and dolomites with beds of [[anhydrite]], gypsum and salt. The salt beds are worked at Hall, Friedrichshall, Heilbronn, Stettin and Erfurt. It is from this division that many of the mineral springs of [[Thuringia]] and south Germany obtain their saline contents. The cellular nature of much of the dolomite has given rise to the term Zellendolomit. The Upper Muschelkalk (Hauptmuschelkalk, Friedrichshallkalk of von Alberti) consists of regular beds of shelly limestone alternating with beds of [[marl]]. The lower portion or Trochitenkalk is often composed entirely of the fragmentary stems of ''Encrinus liliiforrnis''; higher up come the Nodosus beds with ''Ceratites cornpressus, C. nodosus, and C. semipartitus'' in ascending order. In Swabia and Franconia the highest beds are platy dolomites with ''Tringonodus Sandergensis'' and the crustacean ''Bairdia''. [[Stylolite]]s are common in all the Muschelkalk limestones. The Alpine Muschelkalk differs in many respects from that of the type area, and shows a closer relationship with the Triassic [[Mediterranean Sea]].
In addition to the fossils mentioned above, the following are Muschelkalk forms: ''Terebratulina vulgaris, Spiriferina Mantzeln'' and ''S. hirsute, Myophoria vulgaris, Rhynchotites hirundo, Ceratites Munsteri, Ptychites studeri, Balatonites balatonicus, Aspidura scutellate, Daonella Lommeli'', and in the Alpine region several rock-forming [[Algae]], ''Baciryllium, Gyroporella, Diptopora'', etc.
==References==
*{{1911}}
[[Category:Triassic]]
[[Category:Geology of Germany]]
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