Lower Jurassic in the context of "Karoo-Ferrar"

An extensional fault is a fault caused by stretching of the Earth's crust. Stretching reduces the thickness and horizontally extends portions of the crust and/or lithosphere. In most cases such a fault is also a normal fault, but may create a shallower dip usually associated with a thrust fault. Extensional faults are generally planar. If the stress field is oriented with the maximum stress perpendicular to the Earth's surface, extensional faults will create an initial dip of the associated beds of about 60° from the horizontal. The faults will typically extend down to the base of the seismogenic layer. As crustal stretching continues, the faults will rotate, resulting in steeply-dipping fault blocks between them.

The Keuper is a lithostratigraphic unit (a sequence of rock strata) in the subsurface of large parts of west and central Europe. The Keuper consists of dolomite, shales or claystones and evaporites that were deposited during the Middle and Late Triassic epochs (about 220 million years ago). The Keuper lies on top of the Muschelkalk and under the predominantly Lower Jurassic Lias or other Early Jurassic strata.

The Keuper together with the Muschelkalk and the Buntsandstein form the Germanic Trias Group, a characteristic sequence of rock strata that gave the Triassic its name.

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.