Steinheim Basin

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Coordinates: 48 ° 41 ′ 12 ″  N , 10 ° 3 ′ 54 ″  E
Map: Germany
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Steinheim Basin​
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Germany
Steinheim Basin (Baden-Württemberg)
Steinheim Basin
Steinheim Basin
Location in Baden-Württemberg
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Computer-generated 3D representation of the Steinheim basin (3-fold elevated, overlaid with aerial photo)

The Steinheim Basin is an impact crater created by a meteorite impact near Steinheim am Albuch in the Heidenheim district in Baden-Württemberg .

Appearance

The Steinheim basin is almost circular with an average diameter of around 3.8 kilometers. In the center of the basin, a hill, the Steinhirt , rises around 50 meters above today's crater floor, while the crater floor itself is around 100 meters below the surrounding plateau of the Albuch .

The community of Steinheim is located in the crater .

Emergence

The Steinheim Basin was formed about 14-15 million years ago when a meteorite, estimated to be about 100-150 meters in diameter, hit at a speed of about 20 kilometers per second (72,000 km / h). An energy of around 10 18 joules (corresponding to around 18,000 Hiroshima bombs ) was released explosively , which led to immense devastation of large parts of the Eastern Alb . Initially, a crater was created with a depth of around 200 meters, in the center of which the rebounding rock formed a central mountain around 100 meters high . After the impact, a crater lake formed, which later silted up and was drained through the Wental .

Neighboring event

The fossils found in the lake sediments , which are up to 50 meters thick , lead to the conclusion that the Steinheim Basin was created at the same time as the Nördlinger Ries , located around 40 kilometers to the northeast, in the so-called Ries event . According to this, the cosmic body whose impact left the two craters was an asteroid that was accompanied by a smaller satellite . In more recent studies, an iron (or stone-iron) meteorite is assumed to be the Steinheim impactor.

Geology and paleontology

Radiant lime from the Steinheim basin (type locality). Width of the handpiece: 17 cm.
Radiant limestone (shatter cone) in an Upper Jurassic ammonite stone core . Width of the handpiece: 4.5 cm.
Subparallel shock fractures from the Steinheim Basin (type locality). Handpiece width: 8 cm.
Breccia of shattered limestone on the southern rim of the Steinheim Basin.
Miocene snail sand from the Steinheim basin.

The crater wall consists of shifted and tilted Jura - Kalkschollen . Some of the limestones are also shattered and form a breccia of angular fragments of different sizes. Boreholes have shown that the crater floor below the lake sediments is also filled with breccias, which consist of rock material that was thrown up during the impact and then fell back into the crater (relapse breccia). In places, the impact breccias of the Steinheim Basin show a Suevite character. The central mountain consists mainly of limestone and sandstones from the middle and upper Jura , which can only be found at a depth of about 300 meters if stored undisturbed outside the crater.

Radiant limestone was also found in the limestone of the central mountain. These surface structures arise when the pressure wave of the impact passes through the rock. Radiant limestone was first recognized and described in the Steinheim Basin around 1905, but its origin could not be explained. Today they are also known from numerous other terrestrial craters and are considered to be clear indicators of an impact . Impact-related subparallel shock fractures were also found in the Steinheim Basin, but these do not represent a clear indicator of an impact.

The lake sediments are rich in fossils from the Miocene , so that the Steinheim Basin is one of the most important sites for this geological age. In addition to numerous finds of vertebrates (including fish , reptiles , birds and mammals ), the sediments are primarily known for the fossil snail shells found in large numbers (so-called Steinheimer snail sand ). In 1862, the paleontologist Franz Hilgendorf examined the shells of the freshwater snail Gyraulus , a genus from the family of poppy snails , and found that the shell shape slowly changed from the older sediment layers to the younger ones. The snail finds were the first confirmation of the theory of evolution published by Charles Darwin in 1859 .

The Meteor Crater Museum , which opened in 1978 and is also the starting point for a geological hiking trail through the Steinheim Basin, is located in the Steinheim district of Sontheim .

Protected areas

Almost all of the Steinheim Basin is located in protected areas. On the one hand, this is the nature reserve No. 1,278 Steinheim Basin . The NSG was formed by ordinance of May 28, 2014 by the Stuttgart Regional Council and has a size of 426.1 hectares. Around 371 hectares of this area also form part of the FFH area of the same name , which is around 3000 hectares in size.

On the other hand, the landscape protection area Steinheimer Becken with Schäfhalde, parts of the Stuben- and Zwerchstubentales with side valleys and adjacent parts of the terrain . The LSG with the protected area number 1.35.056 has existed since March 20, 1978. It was originally 1,249 hectares in size, but has been reduced accordingly by the designation of the nature reserve.

The total of 8,645 hectares of the Albuch SPA area (bird sanctuary) protrudes east of Steinheim with around 298 hectares into the Steinheim basin, where it overlaps the nature reserve and the FFH area.

gallery

  • The crater seen from the north (aerial view)

  • View from the southern rim of the crater to the area outside the crater

  • The Steinhirt central hill

  • Limestone rocks Wäldlesfels on the summit of the central Steinhirt hill

Panoramas

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Panoramic view of the Steinheim basin and the Zentralberg, seen from the southern edge (Burgstall).
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Panoramic view of the Steinheim Basin, taken from the southern crater wall. On the crater floor in the foreground is the Steinheim district of Sontheim, behind it you can see the Klosterberg, the central mountain of the crater.
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Panorama view from the eastern edge of the northern part of the Steinheim basin with Steinheim. To the left of the residential area is the central mountain, the chain of hills in the background is the western edge of the crater.

reception

The basin is named for the Mars crater Steinheim .

literature

  • Karl Dietrich Adam , The Steinheim Basin - a site of global renown , Steinheim am Albuch: Mayor's Office, 1980.
  • J. Baier: On the discovery and interpretation of the radiant limestone (shatter cones) in the Steinheim impact crater . In: Geohistorische Blätter , Vol. 29, 2018, pp. 55–68.
  • J. Baier: A Contribution to Shatter Cone Formation (Steinheim Impact Crater, Germany) . In: Exposure . Vol. 69, No. 6, 2018, pp. 370–376.
  • J. Baier: Geological features in the Albuch. In: fossils. Special volume Geopark Schwäbische Alb, 2015, pp. 47–51.
  • J. Baier: The geological nature trail in the Steinheim basin - a cosmic search for traces. In: fossils. Volume 30, No. 4, 2013, pp. 26-31.
  • J. Baier: The Steinheimer Schneckensand - a Miocene fossil deposit of world format. In: fossils. Volume 29, No. 6, 2012, pp. 368-371.
  • J. Baier, VJ Sach: Shatter cones from the impact craters Nördlinger Ries and Steinheimer Becken . In: Fossilien , Volume 35, No. 2, 2018, pp. 26–31.
  • J. Baier, A. Scherzinger: The new geological nature trail in the Steinheim impact crater . In: Annual reports and communications from the Upper Rhine Geological Association. Volume 92, 2010, pp. 9-24, doi : 10.1127 / jmogv / 92/2010/9 .
  • EPJ Heizmann, W. Reiff: The Steinheimer Meteor Crater . Pfeil, Munich 2002, ISBN 3-89937-008-2 .
  • CR Mattmüller: Ries and Steinheimer Basin . Enke, Stuttgart 1994, ISBN 3-432-25991-3 .
  • D. Stöffler, NA Artemieva, E. Pierazzo : Modeling the Ries-Steinheim impact event and the formation of the moldavite strewn field. In Meteoritics & Planetary Science . Volume 37, 2002, pp. 1893-1907 ( PDF file ).
  • M. Schmieder, E. Buchner: Fe-Ni-Co sulfides from the Steinheim Basin, SW Germany: Possible impactor traces. In: 72nd Annual Meteoritical Society Meeting (2009). abstract no.5073 ( PDF file; 20 kB ).
  • E. Buchner, M. Schmieder: Steinheim suevite - A first report of melt-bearing impactites from the Steinheim Basin (SW Germany). In: Meteoritics & Planetary Science. Volume 45, No. 7, July 2010, pp. 1093-1107, doi : 10.1111 / j.1945-5100.2010.01073.x .
  • VJ Sach, J. Baier: New investigations on radiant limestone and shatter cones in sedimentary and crystalline rocks (Ries impact and Steinheim impact, Germany) . Munich 2017, ISBN 978-3-89937-229-8

Web links

Commons : Steinheim Basin  - Album with pictures, videos and audio files

Individual evidence

  1. ^ Mattmüller, 1994
  2. ↑ a b Stöffler, Artemieva and Pierazzo, 2002
  3. ↑ a b Baier and Scherzinger, 2010
  4. ↑ a b Schmieder and Buchner, 2009
  5. ↑ Baier and Sach, 2018
  6. ↑ Sach and Baier, 2017
  7. ↑ Baier, 2018
  8. ↑ Baier, 2012
  9. ^ Heizmann and Reiff, 2002