The area is characterized by a series of low-relief Jurassic horsts and graben. |
The classic example has been the Rhine Valley graben with the Vosges Mountains and the Schwarzwald as adjacent horsts. |
Often, the tectonic action of crustal extension has created an alternating series of parallel grabens and horsts that form elongate basins alternating with mountain ranges. |
Innumerable faults, in fact, cut through the country, many bounding secondary grabens and horsts. |
A thinner series of these rocks occurs on top of horsts of Jurassic rocks. |
Fault movements by which blocks of terrain move up or down relative to each other, as when horsts or grabens are formed, can also produce inliers and outliers. |