Sand pit Riedern am Sand

"Obere Brackwassermolasse" or Obere Meeresmolasse of the southwest of the Molasse basin in the Riedern sand pit: barley sands and overlying, clearly weathered oyster nagelfluh.

Map of the Alpine foothills with the course of the barley sand channel. Riedern is located at the transition from the channel to what was then the Molasse Sea

Fossil teeth from the Riedern sand pit

The sand pit Riedern am Sand or sand pit Riedern is an artificially expanded outcrop of honey-yellow quartz sand or quartz gravel. The former mining site is about 560  m above sea level. NHN on the eastern flank of the Kätzler ( 596  m above sea level ), approx. 750 m southwest of Riedern am Sand in Klettgau .

geology

Before its uplift in the highest Miocene in the course of the final phase of the formation of the Alps, the northern foothills of the Alps (regional geologically: Molasse basin ) was covered several times by the sea. In the western wall of the abandoned Riedern sand pit, a several-meter-thick profile of deposits from the higher Lower Miocene ( Burdigalium ) is cut, which documents the most recent of these sea invasions.

These are so-called barley sands ("Grimmelfinger layers") and overlying Austernnagelfluh. While the barley sands are considered to be brackish formation ("Obere Brackwassermolasse", OBM), the Austernnagelfluh is considered to be fully marine and is assigned to the Upper Marine Molasse (OMM).

The honey-yellow to reddish color of the barley sands is probably due to the finely distributed precipitates of iron oxides and hydroxides in the sediment. The erosive Ausernnagelfluh is much more weather and erosion resistant than the barley sand and therefore forms an overhang in the quarry wall. In the Klettgaualb , the Austernnagelfluh often forms a characteristic step in the terrain.

Fossils

What is special about the barley sands in the Riedern sand pit is their comparatively high fossil content. It has long been known to fossil collectors as the location of shark teeth and has been searched accordingly. The teeth of land mammals, such as beavers and dwarf deer, are much less common . Since the mining has long been discontinued, finds are hardly possible any more. There is also a risk of falling rocks and slipping on the steep face.

Historical

The sand was used as construction sand, mainly for plastering work , in particular as a trowel , which was possible in many variants by sieving the sand in different grain sizes. A sand chute and a silo were built around 1920 for dismantling. Small remains of it are still visible.

See also

• Napfbergland
• Erminger Turritellenplatte
• Rand coarse limestone
• Tennikerfluh
• Ramminger sand pit

Literature and maps

• Christian Birchmeier: Stone ore mining in the southern rim. New year's paper of the Schaffhausen Natural Research Society , 1986
• Hans Schneider: About recent crust movements in the pre-Alpine landscape between the southern Rhine rift and Lake Constance. Announcements from the Schaffhausen Natural Research Society. 1973/75
• Hubert Roth: Waisch it noh? Klettgau - as it used to be. 1986, ISBN 3 89264 014 9
• Geological map of Switzerland 1: 500,000. Swiss Geological Commission, 1980.
• Hans Heierli: Geological hiking guide Switzerland. Part 1: The geological basics. 2nd Edition. Ott, Thun 1983, ISBN 3-7225-6282-1 .

Web links

• Brief description of the Riedern sand pit on the Environment Theme Park web portal . The photo contained therein shows very nicely the erosive cutting of the Austernnagelfluh into the barley sands.
• Riedern am Sand on Mineralienatlas.de

Individual evidence

1. ^ VJ Sach, EPJ Heizmann: Stratigraphy and mammalian faunas of the brackish water molasses in the area around Ulm (southern Germany). Stuttgart Contributions to Natural History, Series B. No. 310, 2001, p. 6 ( PDF ).
2. ↑ Hubert Roth: Waisch es noh? Klettgau - as it used to be. P. 74f.

Coordinates: 47 ° 37 ′ 15 ″  N , 8 ° 26 ′ 10 ″  E