Middle Jurassic

The Middle Jurassic (or Middle Jurassic ) is the mean chronostratigraphic series of Jura in the Earth's history. In the older literature, z.T. even in the popular scientific literature, this series also commonly known as Dogger or Brown Jura ( Jura Brown ) is called. In the Süddeutsche law, the term is used in the Brown Jurassic lithostratigraphic division ( in the sense of a group of formations ) on. Also, the term Dogger is still used for lithostratigraphic subdivision of the North German law. The series of Middle Jurassic is underlain by the series of the Lower Jurassic and overlaid by Upper Jurassic. It corresponds approximately to the period from 174.1 million to 163.5 million years years.

Older names

In previous scientific work, but especially in the popular scientific literature (some even today ) this period of Earth's history mostly as Brauner Jura ( Jura Brown ) or Dogger is called. However, this is not correct, since two different stratigraphic subdivisions ( chronostratigraphy and lithostratigraphy ) are mixed. The lithostratigraphic unit of the Brown Jurassic in southern Germany is characterized primarily by iron leading brown sandstones and clays. Since the deposits of the Brown Jura regional use before the beginning of the Middle Jurassic, and in many areas of the South German law clearly extend into the Upper Jurassic in, the lithostratigraphic term Brauner Jura is not exactly synonymous with the chronostratigraphic Middle Jurassic series.

Also, the term Dogger is still frequently used for the series of Middle Jurassic. The name comes from the English Dogger quarry industry. He is now reserved in the form of North German Dogger provisionally for a lithostratigraphic group in the Middle Jurassic of northern Germany. However, North German Dogger in central and northern Germany is not yet finally decided on the boundaries and use of the lithostratigraphic unit.

Subdivision

The series of Middle Jurassic is divided into the following chronostratigraphic stages:

• System: Jurassic ( 201.3 to 145 mya ) Series: Upper Jurassic ( 163.5 to 145 mya )
• Series: Middle Jurassic ( 174.1 to 163.5 mya ) Level: Callovian ( 166.1 to 163.5 mya )
• Level: Bathonian ( 168.3 to 166.1 mya )
• Level: Bajocian ( 170.3 to 168.3 mya )
• Level: Aalenian ( 174.1 to 170.3 mya )

Faunas

In the Middle Jurassic, there was warm climate, and Ammonites, as in the entire Jura important index fossils, the basis of which, the further biostratigraphic fine subdivision of the steps. In the Middle and Upper Jurassic the first lizards emerged.