Brown Jura

The Brown Jurassic or Brown Jura in earth history refers to the middle 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 Middle Jurassic. This is however not quite correct, because the Brown Jura does not exactly coincide with the chronostratigraphic boundaries of the Middle Jurassic. In addition, the term Dogger, which was formerly frequently used as a synonym should no longer be used in connexion with the South German Jurassic. Instead the term "Dogger" should be reserved for the roughly equivalent lithostratigraphic unit in the North German Jurassic. The Brown Jurassic was deposited about 175-161 million years ago. The Brown Jurassic follows the lithostratigraphic unit of the Black Jurassic and is superimposed on the lithostratigraphic group of the White Jurassic.