The Triassic is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.9 million years ago (Mya), to the beginning of the Jurassic Period 201.3 Mya. The Triassic is the first and shortest period of the Mesozoic Era. Both the start and end of the period are marked by major extinction events.
The Early Jurassic epoch is the earliest of three epochs of the Jurassic period. The Early Jurassic starts immediately after the Triassic-Jurassic extinction event, 201.3 Ma, and ends at the start of the Middle Jurassic 174.1 Ma.
The Muschelkalk is a sequence of sedimentary rock strata in the geology of central and western Europe. It has a Middle Triassic 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 Keuper. The Muschelkalk consists of a sequence of limestone and dolostone beds.
The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 251.902 Ma and 247.2 Ma. Rocks from this epoch are collectively known as the Lower Triassic, which is a unit in chronostratigraphy. The Early Triassic is the oldest epoch of the Mesozoic Era and is divided into the Induan and Olenekian ages.
The Keuper is a lithostratigraphic unit in the subsurface of large parts of west and central Europe. The Keuper consists of dolostone, shales or claystones and evaporites that were deposited during the Middle and Late Triassic epochs. The Keuper lies on top of the Muschelkalk and under the predominantly Lower Jurassic Lias or other Early Jurassic strata.
Alderley Edge in Cheshire is one of the classic locations for the study of Triassic sandstones in the United Kingdom]. Numerous scientists from the early 19th century up to the present day have studied the area and it is a popular field site for universities around the UK.
The Rotliegend, Rotliegend Group or Rotliegendes is a lithostratigraphic unit of latest Carboniferous to Guadalupian age that is found in the subsurface of large areas in western and central Europe. The Rotliegend mainly consists of sandstone layers. It is usually covered by the Zechstein and lies on top of regionally different formations of late Carboniferous age.
The Buntsandstein or Bunter sandstone is a lithostratigraphic and allostratigraphic unit in the subsurface of large parts of west and central Europe. The Buntsandstein predominantly consists of sandstone layers of the Lower Triassic series and is one of three characteristic Triassic units, together with the Muschelkalk and Keuper that form the Germanic Trias Supergroup.
The Upper Keuper or Rhätsandstein (Rhätsandstein) is a lithostratigraphic subgroup of the Keuper in the Germanic Trias. It currently has only one formation, the Exter Formation. The lithostratigraphic unit is underlain by the Middle Keuper subgroup and overlain, in the North German Basin, by the Lias and, in the South German Basin by the Black Jurassic.
The Pyrenees are a 430-kilometre-long, roughly east–west striking, intracontinental mountain chain that divide France, Spain, and Andorra. The belt has an extended, polycyclic geological evolution dating back to the Precambrian. The chain's present configuration is due to the collision between the microcontinent Iberia and the southwestern promontory of the European Plate. The two continents were approaching each other since the onset of the Upper Cretaceous (Albian/Cenomanian) about 100 million years ago and were consequently colliding during the Paleogene (Eocene/Oligocene) 55 to 25 million years ago. After its uplift, the chain experienced intense erosion and isostatic readjustments. A cross-section through the chain shows an asymmetric flower-like structure with steeper dips on the French side. The Pyrenees are not solely the result of compressional forces, but also show an important sinistral shearing.
The Erfurt Formation, also known as the Lower Keuper, is a stratigraphic formation of the Keuper group and the Germanic Trias supergroup. It was deposited during the Ladinian stage of the Triassic period. It lies above the Upper Muschelkalk and below the Middle Keuper.
The North German Basin is a passive-active rift basin located in central and west Europe, lying within the southeastern most portions of the North Sea and the southwestern Baltic Sea and across terrestrial portions of northern Germany, Netherlands, and Poland. The North German Basin is a sub-basin of the Southern Permian Basin, that accounts for a composite of intra-continental basins composed of Permian to Cenozoic sediments, which have accumulated to thicknesses around 10–12 kilometres (6–7.5 mi). The complex evolution of the basin takes place from the Permian to the Cenozoic, and is largely influenced by multiple stages of rifting, subsidence, and salt tectonic events. The North German Basin also accounts for a significant amount of Western Europe's natural gas resources, including one of the worlds largest natural gas reservoir, the Groningen gas field.
The Black Jurassic or Black Jura in earth history refers to the lowest of the three lithostratigraphic units of the South German Jurassic, the latter being understood not as a geographical, but a geological term in the sense of a lithostratigraphic super group. Formerly and even occasionally today in the popular scientific literature, this term is equated to the chronostratigraphic series of the Lower Jurassic. This is however not quite correct, because the Black Jura does not exactly coincide with the chronostratigraphic boundaries of the Lower Jurassic. In addition, the term lias, which was formerly frequently used as a synonym, should no longer be used in connexion with the South German Jurassic. Instead, the term lias, or North German Lias, should be reserved for the roughly equivalent lithostratigraphic unit in the North German Jurassic. The deposition of the Black Jurassic took place about 199 to 175 million years ago. The Black Jurassic follows the lithostratigraphic unit of the Keuper and is superimposed on the lithostratigraphic group of the Brown Jurassic.
The geology of Germany is heavily influenced by several phases of orogeny in the Paleozoic and the Cenozoic, by sedimentation in shelf seas and epicontinental seas and on plains in the Permian and Mesozoic as well as by the Quaternary glaciations.
The Worcester Basin or Worcester Graben is a sedimentary basin in central England, filled with mainly Permian and Triassic rocks. It trends roughly north-south and lies between the East Malverns Fault in the west and the Inkberrow Fault in the east. It forms part of a series of Permo-Triassic basins that stretch north-south across England, including the Cheshire Basin and the East Irish Sea Basin. These basins resulted from a regional rifting event that affected parts of North-West Europe, eastern North America and East Greenland.
The Bridport Sand Formation is a formation of Toarcian age found in the Worcester and Wessex Basins of central and southern England. It forms one of the reservoir units in the Wytch Farm oilfield in Dorset. The sandstone is very-fine grained to fine-grained and contains regular narrow bands that are calcite-cemented and more resistant to weathering, giving it a characteristic banded appearance at outcrop, such as in the cliffs between Bridport and Burton Bradstock in Dorset. It is named for Bridport and has previously been known as the Midford Sand(s), Cotteswold Sands, Yeovil Sands and Upper Lias Sand(s). It forms a locally important aquifer, particularly around Yeovil.
