Ramminger sand pit

Inclined and cross layers in the Ramming sand pit, visually accentuated by "Liesegang bands".

Detail: Coarse-grained, diagonally layered sandstone superimposes fine-grained sandstone with marly inclusions. With regard to the "Liesegang bands", it is easy to see that the precipitation fronts run partly parallel to the stratification, but partly also perpendicular to the stratification.

The Ramminger sand pit is an artificial outcrop near Rammingen in the Alb-Donau district in Baden-Württemberg , where building sand was previously mined. The weakly consolidated sandstone was formed around 20 to 15 million years ago in the Miocene , when the Molasse Sea covered, among other things, Upper Swabia and part of the Swabian Alb .

The sand pit is managed as a protected geotope by the State Institute for the Environment, Measurements and Nature Conservation Baden-Württemberg under the name of Aufgelassene Sandgrube Sandäcker . It is also protected as a natural monument under the name Former Sand Pit .

Explanation description

In the north wall of the former sand pit, an approximately five-meter-thick profile of the Upper Sea Molasse (OMM) is exposed. These are mostly carbonate cemented , predominantly lightly solidified sandstones that contain small pebbles and mussel shells. In places, oblique stratification is clearly visible. The main identifiable fossils are the remains of marine molluscs , primarily oysters of the Crassostrea giengensis species, as well as tower snails and cockles . In addition to the sloping structures, cross- layers can also be found in the outcrop . These are caused by the changing directions of the seawater flow, such as occur in tidal areas due to the tidal rhythm.

"Liesegang bands"

The rust-brown stripes that are visible in places in the sandstone are called "Liesegang bands". They trace the sedimentary stratification and visually accentuate it. However, they only emerged after the sandstone had deposited (compare: Liesegang rings ). This can be determined by the fact that, in some cases, the staining stops abruptly in the case of several layers lying directly on top of one another. Such a phenomenon cannot possibly arise from sedimentation processes. The Liesegang bands were formed by the precipitation of iron dissolved in the pore water, which was washed out of the rock layers above. The boundary between “colored” and “uncolored” rock is called the precipitation front .

Web links

Data evaluation sheet and map in the profile of the extensive natural monument in the protected area directory of the LUBW

Individual evidence

^ ^A ^b Manfred Schöttle, Hans-Dieter Bergner, Georg Burgmeier, Thomas Huth: Geotopes in the administrative region of Tübingen, profiles. LUBW State Institute for the Environment, Measurements and Nature Conservation Baden-Württemberg, Karlsruhe 2007, Appendix: District Alb-Donau-Kreis, p. 45 ( online , p. 184 in PDF)

48.526194 10.163211Coordinates: 48 ° 31 '34.3 " N , 10 ° 9' 47.6" E

[LUBW-1] A ^b Manfred Schöttle, Hans-Dieter Bergner, Georg Burgmeier, Thomas Huth: Geotopes in the administrative region of Tübingen, profiles. LUBW State Institute for the Environment, Measurements and Nature Conservation Baden-Württemberg, Karlsruhe 2007, Appendix: District Alb-Donau-Kreis, p. 45 ( online , p. 184 in PDF)