Protection rock Pentling
The protective rock Pentling is a rock face near Sinzing , in the Upper Palatinate district of Regensburg in Bavaria .
location
The rock face is located in the municipality of Pentling , about 800 meters east of Sinzing. It is located above the Danube on the southern edge of one of the oldest nature reserves in Bavaria, the Max-Schultze-Steig . The rock face is also part of the FFH area dry slopes near Regensburg .
description
The Schutzfelsen is the type locality of the so-called Schutzfels-Formation. This sequence of layers of clayey-sandy material was deposited in a karst hollow form in massive limestone from Upper Jurassic in the Lower Cretaceous Period . Since these deposits from the Lower Cretaceous Period are not very resistant to erosion, a half-cave , the protective rock cave , has formed in them . The overhanging roof of this half cave is formed by the Upper Cretaceous green sandstone of the Regensburg formation , at the base of which a transgression conglomerate is formed.
To the south of Regensburg , the Danube has cut into the Jura and Chalk rocks. In the lower area of the Danube bank slope, karst limestone of the Upper Jura often form steep rocky cliffs. Regensburg green sandstone lies above it.
The protective rock near Pentling gave its name to a previously unknown sequence of rocks, the protective rock formation. The name Schutzfelsen goes back to the botanist David Heinrich Hoppe . During a storm he looked for shelter under the rock roof. Later, on May 14, 1790, he and Naturefriends founded the oldest still existing botanical association in the world, the Regensburg Botanical Society . In memory of him, the protective rock is also called "Hoppefelsen". A memorial plaque was placed on the rock in 1790 in honor of David Heinrich Hoppe. It was renewed in 1890 and is designated as an architectural monument by the Bavarian State Office for the Preservation of Monuments (D-3-75-180-22).
Protective rock formation
The protective rock formation is also called protective rock sandstone, protective rock layers, Amberg layers or Amberg ore formation. In 1854, the Bavarian geologist Carl Wilhelm Gümbel first described the rocks lying between the Jurassic limestone and Regensburg green sandstone on the protective rock and named them after him as protective rock layers. This made the protective rock a type locality. In 1935 Ferdinand Trusheim revised the publication. Sands and colorful clays of the so-called protective rock layers are the oldest Cretaceous sediments in this area. In general, it is unconsolidated, clastic sediments ( clays , silts , sands, gravels) that can be partially consolidated. The binding agent is either kaolinitic (then the sediment resembles a kaolinized arkose ) or pebbly (so that there are quartzitic sandstones). The quartz content is 90–95%, feldspars and carbonate are mostly absent. The sediments are usually pure white, yellowish or greenish. Abundant organic matter can also turn them black. However, bright red, purple to blue is particularly noticeable. The pebbles can reach a diameter of 4 to 5 cm, black lydites can be common. Marcasite tubers with shelled-concentric structure and silicification are uncommon. The protective rock formation is widespread in Bavaria ( Upper Palatinate , Lower Bavaria , Upper Bavaria , Swabia , Middle Franconia , Upper Franconia ). As a relic of erosion in karst chutes , the protective rock formation is today mainly associated with the spread of the Malm limestone. The southernmost occurrence is near Abensberg 30 km south of Regensburg . In the north, the protective rock formation extends far beyond Auerbach . In Flinsbach (Passau) the easternmost occurrence should be. Between Neuburg on the Danube and Solnhofen , the protective rock formation formed the surface of the Wellheim formation before the karst chutes collapsed . The formations emerged during the Lower Cretaceous when the long karstification period was interrupted by a phase in which rivers increasingly carried sand and clays from the eastern Bavarian basement and deposited them. Even before the sea advance of the Upper Cretaceous, these layers were almost completely removed. Remnants were only preserved in the caves, sinkholes and karst depressions of that time.
The exact age of the protective rock layers could not yet be determined. They hardly contain any fossils that would allow an exact chronological assignment.
Protective rock cave
The Schutzfelsenhöhle is located in the rock face on the Schutzfelsen as a half-cave about thirteen meters wide, up to five meters deep and about four meters high. The roof of the rock overhang consists of Regensburg green sandstone, underneath the Cretaceous protective rock layers lie in a former karst depression in the mass limestone. It is listed in the Franconian Alb cave register as "I 77".
The time of the chalk
During the time of the Upper Jura , large parts of southern Germany lay in the area of a tropical flat sea, which was followed by an open ocean in the south. The mighty limestone and dolomite rocks that form the Franconian Jura today were formed in this shallow sea . At the end of the Jura, the sea receded far to the south and the shallow sea area became the mainland. Tropical weathering and erosion prevailed in the Lower Cretaceous for the next 40 million years. The limestone and dolomites of today's Alb table karstified profoundly. The result was a landscape that is familiar from today's tropical karst areas. At the time of the Upper Cretaceous about 95 million years ago, the sea flooded the mainland again from the south. As a result, fossil-rich sandstones (Regensburg green sandstone) were initially deposited in the area of the Regensburg Bay . Above that follow sandstones, marls and limestone from the Upper Cretaceous.
Geotope
The rock face has been designated by the Bavarian State Office for the Environment (LfU) as a geoscientifically valuable geotope (geotope number: 375R032). It was also awarded the official seal of approval for Bavaria's most beautiful geotopes by the LfU .
Individual evidence
- ↑ Location of the geotope in the Bavaria Atlas (accessed December 10, 2017).
- ↑ Protected Planet: dry slopes near Regensburg. Accessed December 10, 2017 (English).
- ↑ 6938-301 dry slopes near Regensburg. (FFH area) Profiles of the Natura 2000 areas. Published by the Federal Agency for Nature Conservation . Retrieved December 10, 2017.
- ↑ Lithostratigraphic Units of Germany, Schutzfels Formation (accessed on December 11, 2017)
- ^ Bavarian State Office for the Environment, Geotop Schutzfelsen NW von Pentling (accessed on December 10, 2017).
- ↑ Bavaria's most beautiful geotopes, Schutzfelsen Pentling (accessed December 10, 2017)
Web links
Coordinates: 48 ° 59 ′ 32.5 ″ N , 12 ° 2 ′ 47.9 ″ E