Station: [26] Franconian Scarplands

The Franconian Scarplands are part of the South German Scarplands, which extend from northern Franconia far into southwestern Baden-Württemberg. A typical feature of scarplands is alternating rock formations that are susceptible to different degrees of weathering.

Sandstones, limestones and dolomites form especially robust and weather-resistant scarps, or escarpments – whereas rocks rich in clay minerals are softer and easily destroyed.

If the strata were deposited horizontally, the same unstable rocks would always be found in the valleys and the same stable rocks on the plateaus. But because they are slightly tilted, the strata of the first level dip into the subsoil before those in the next level.

We have a selection of Franconian Scarplands rocks on display here. During an earlier period of the earth's history, called the Triassic, rivers transported sand or clay sludge from the surrounding heights into a wide inland basin. The last sediments to be deposited during this geological period were called "Feuerletten", literally fire clays, because of their red colour. This was also the environment in which plateosaurs roamed in search of their plant-based diet.

At the beginning of the Jurassic period, South Germany was beneath the sea. The first sediment to be deposited in that sea was the fine-grained Lias sandstone. The Jurassic formation is traditionally divided into the Black, Brown and White Jurassic. Dark mudrocks, or argillites, are often found in the Black Jurassic.

From the start of the Jurassic period, remains of marine animals are found in the rocks. The ammonite bank discovered in the Posidonia formation is especially spectacular. This unusual collection of shells was probably piled up during a tsunami.

In the Brown Jurassic, sandstones put in their final appearance. Subsequently, in the White Jurassic, the nature of the deposits is determined by sea creatures. The White Jurassic limestone is essentially made up of tiny plankton shells that remain invisible even under a magnifying glass. All the naked eye can see is pale rock, which forms the escarpment of the Franconian Alps and is distinctive even from a distance.