The Black Jurassic or Black Jura (German: Schwarzer 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 (and sometimes is today) 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.
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👉 Black Jurassic in the context of Early Jurassic
The Early Jurassic Epoch (in chronostratigraphy corresponding to the Lower Jurassic Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic–Jurassic extinction event, 201.3 Ma (million years ago), and ends at the start of the Middle Jurassic 174.7 ±0.8 Ma.
Certain rocks of marine origin of this age in Europe are called "Lias" and that name was used for the period, as well, in 19th-century geology. In southern Germany rocks of this age are called Black Jurassic.