Astroblème de Ries

The Astroblème of Laugh (name German: Nördlingen Ries ) is a depression in the west of the Bavaria, in Germany, located at the north of the the Danube, in the district of Donau-Laugh.

The toponym “Laugh” comes from the name of the Roman province “Rætia”. Laugh is almost circular and its flat character is distinguished in a way surprising of the broken landscape from Franconie and Souabe. On the basis of rock found in Laugh, in particular the Suévites, it was initially regarded as an old volcano. In 1960 only, one could prove that it was about an impact of Météorite old of approximately 15 million years. It counts among the meteoritic craters most important on the surface of the ground.

Description

Nördlinger Ries is almost circular (approximately 22 X 24 kilometers). The crater does not appear clearly because of its dimension and wind erosion. Ground, one sees the edge the crater like a kind of range of hills which runs around the horizon and glaze of forests. The ground of the current crater is to approximately 100 to 150 meters below the culminating points the préalpes franconienne and souabe. Inside, a circular range of hills is noticed (internal fill, ring interns or crystalline ring) which differentiates Nördlinger Ries from the other meteoritic impacts. In the ring interns, one can see Marienhöhe (“Hill of Marie”) close to Nördlingen, the rocks of Wallerstein or the “Wennenberg” close to Alerheim. In Nördlinger Ries one finds some cities and municipalities: Nördlingen, Harburg, Öttingen etc an affluent of the the Danube crosses it its many meanders: the Wörnitz.

Origin

Old theories

The particular geological characteristics of Laugh intrigued the geologists during several centuries. Various attempts at explanations were born. The presence of suévite and pumice tuff a long time made privilege the theory of the volcano, in 1805 Mathias von Flurl, founder of geology in Bavaria defines thus Laugh it like an old volcano.

In 1870, Carl Wilhelm von Gümbel studies the distribution of the suévite in the crater and concludes some with the existence from one “Laugh-Vulkan” which however completely disappeared during the Histoire from the Earth, so that there are nothing any more but the rocks ejected by him which are observable.

In 1901, Wilhelm Branco and Eberhard Fraas try to show, that it was not about a volcano. An underground magmatic room would have initially raised the basement before being invaded by water by explosive evaporations.

Since 1910, an officer, Walter Kranz, shows by experiments of dynamiting, that Laugh it is the result of only one central explosion. But he considered that it was the result of a volcanic explosion.

Beside the volcanic theories, one considers also the effect of a glacier (Deffner in 1870) or the plate tectonics in connection with the birth of the Alps.

In fact, nobody at the time could explain in a final way all the characteristics of Laugh.

But in 1904, already, Ernst Werner puts forth the assumption of a meteoritic impact as probable explanation of the birth of Laugh, and in 1936 Otto Stutzer highlights similarities between Meteor Crater in Arizona and Laugh it.

The theory of the meteoritic impact

In 1960, the geologists American Eugene Shoemaker and Edward Chao finally could prove, by the analysis of the rocks, that the crater of Laugh came well from a Astroblème. Indeed, the two modifications of quartz, due to very strong pressures, cannot come from a volcanic activity. By studying more particularly the Stishovite and the Coésite, they deduce the origin from it meteoritic from Laugh, 15 million years ago.
The meteorite could have a diameter of approximately 1,5 km. Its impact speed is estimated at 20 km/s (72 000 km/h). The explosion which results from it is equivalent to 1,8 million times the bomb of Hiroshima. 150 km ³ of rocks were ejected basement. Stones were projected on a distance of 70 km. One found Tectite S to 450 km of the impact. In a few minutes, it was formed a crater 25 km in diameter and deep from approximately 500 Mr. About any form of life in a ray of at least 100 km disappeared suddenly. With time, the crater filled of water on a surface of approximately 400 km ², which did one of the more European big lakes of them. Without flow of salts, the lake had the salinity of the current seas. During the two million following years, the lake was emptied. It is only at the Ice Age, that it erodes and covered with Lœss, which makes Laugh a particularly fertile agricultural zone.

Related events

To approximately 40 km in the south-west of Nördlinger Ries the crater of Steinheim is, 3,5 km in diameter. It would also go back to approximately 15 million years and would be thus contemporary same event that Laugh it. It is possible that the same asteroid disintegrated in two parts and left two distinct impacts.

Geology

Nördlinger Ries belongs to the great meteoritic impacts best preserved on ground. Its importance from the geological point of view is thus considerable, as well about the hidden rocks as ejected. The astronauts of the missions of NASA Apollo 14 and Apollo 17 remained from August 10th to 14th 1970 there to familiarize themselves with the lunar relief and the sampling of rocks, under the control of Wolf von Engelhardt, Dieter Stöffler and Günther Graup which initiated them with the characteristics of the rocks of a meteoritic crater.

Crystallography

A second circular line of hills is inside crater. The base of these hills is composed of granite and other magmatic rocks disaggregated in the form of sand. One occasionally finds cones of percussion which were formed just after the impact of the meteorite. The central ring comes from the deposit of the rocks after the rebound. The crystalline basement is to 300 or 400 m below. The same configuration is also found with the Cratère of Steinheim.

Multicoloured agglomerates

These multicoloured rocks form the mass of ejection (“ejecta”) principal of Laugh. They were projected by the explosive evaporation of the meteorite, often with several kilometers of altitude (ballistic ejection). They are primarily sedimentary rocks of the Mesozoic . These agglomerates, which can measure 100 m, are found until a distance of 40 km around Laugh.

Suévites

The suévites are characteristic of the rocks resulting from the impact from Laugh. They contain some minerals which appear only under conditions of pressures and temperatures extremely high: Stishovite, Coésite and crystals. Surveys in Laugh showed that the crater contains suévites on 400 m of depth. Outside the crater, deposits isolated from suévites are visible in the multicoloured agglomerates.

Blocks of Reuter

The blocks of Reuter are blocks of Calcaire dating from Jurassic which were expelled very quickly of the crater and which flew away up to 70 km with the round, although some weigh approximately 100 kg. One still currently find them close to Augsburg and Ulm. They are named thus according to legéoloque inhabitant of Munich Lothar Reuter who studied them and referred.

Moldavite

One finds tektites as the moldavite with 250 - 400 km of Laugh, in Bohemia and Moravie. They are molten Silicate S of vitreous aspect, produced by an high temperature. The bond with Laugh was proven by experiments on the age of these tektites and projectiles subjected to a strong acceleration. Today, it is believed that these tektites were formed some Milliseconde S before the impact, when the roadbase of terrestrial surface, melted, was projected towards the east at a very high speed.

Marine sediments

Nowadays, the interior of the crater is almost completely filled with the Sédiments of the old lake of Laugh. The clay stone deposits reach a 400 m depth and recover the suévites repercussions after the impact. Fossile S testify however to an aquatic life during the Miocène. One frequently found shells of small water slugs and oysters. Various sites conceal fossils of birds, reptiles, fish and mammals. The flora is represented by fossils of algae, reeds and sheets of trees.

Geological profile

Auswurfdecke : external layer
Mega-block zone: zone of large rocks
Innerer boxing ring: ring interns
Kraterrand: edge of the crater

multicoloured Agglomerates
Ground of crystallized rocks
Suevite: suévites
Sorted: Sorted
Seesediment: marine sediments
the Jura: Jurassic

Settlement

According to the archaeological excavations, the settlement of Laugh goes back to 40.000 years, with the Paléolithique. On two sites on the edge of the crater, close to Nördlingen, one discovered 33 human craniums gone back to approximately 10.000 years.

The Romains established three “castrum” on Laugh, to 20 km in the south of the Limes. The excavations prove the existence of civil populations near the camps. These populations were devoted to artisanal and commercial activities. The Roman province was called “Raetia”, word at the origin of current name “Laugh”.

In 259, the Alamans drive out the Romans. They are at the origin of the current populations of Souabe.

Environment

The crater itself is primarily dedicated to agriculture, and slightly wooded. On the other hand, the edges are covered with wooded large surfaces.

Flora

In the south and the west of the crater, more or less important surfaces of Lande are covered with Bruyère and Genévrier. They are classified natural reserves.

One also finds, like typical plants:

the annual seseli (Seseli annuum)
the eyelet of the Carthusian monks (Dianthus carthusianorum)
the stemless Carline (Carlina acaulis)
the Spiranthe of autumn (Spiranthes spiralis) (rare)
the dictamme (Dictamnus albus)
the verticillate Illécèbre (Illecebrum verticillatum)

Since the beginning of the years 1990, Laugh it is the object of a project of extensive agriculture. On certain pieces new specific plants appeared: The Adonis of summer (Adonis aestivalis), the brown Nonée (Nonea pulla) and the Venus mirror (Legousia speculum-veneris).

Tourism

Nördlinger Ries is an important tourist center. The great number of Japanese tourists is particularly surprising. Indeed, the historical center of the old city of Nördlingen is gravitational for tourists, in the same way the proximity of the crater of Laugh and the museum “Rieskrater-Museum” which is dedicated to him there. The “Stadtmuseum” of Nördlingen, the Bavarian museum of the railroad and the museum of the rural life with Maihingen are very appreciated curiosities. Laugh is on the romantic Route close to the towns of Nördlingen, Harburg and Donauwörth. Albstrasse Schwäbische (the road of High Souabe) ends with Nördlingen. Moreover Laugh it is a “Naherholungsgebiet” (= “area of holiday near a big city”

Bibliography (primarily in German)

J. Baier: Die Auswurfprodukte of Laugh-Impakts, Deutschland , in Documenta Naturae , vol. 162, München, 2007. ISBN 978-3-86544-162-1, ISSN 0723-8428
G. Graup: Carbonate-silicate liquid immiscibility upon impact melting: Laugh Crater, Germany , in Meteorit. Planet. Sci. , vol. 34, Lawrence, Kansas, 1999.
G. Graup: Terrestrial chondrules, knell spherules and accretionary lapilli from the suevite, Laugh crater, Germany , in Earth Planet. Sci. Lett . , Vol. 55, Amsterdam, 1981.
G. Graup: Untersuchungen zur Genese of Suevits im Nördlinger Laugh , in Fortschr. Mineral . , Vol. 59, Bh. 1, Stuttgart, 1981.
C.W. Gümbel: Über den Riesvulkan und über vulkanische Erscheinungen im Rieskessel , in Sitzungsberichte DER maths. - phys. Class der Bayerischen Akademie der Wissenschaften , München, 1870
C. Deffner: Der Buchberg EIB Bopfingen , in Jahreshefte of Vereins für vaterländische Naturkunde in Württemberg , Band 26, Stuttgart, 1870
W. Branco, E. Fraas: Das vulcanische Laugh EIB Nördlingen in seiner Bedeutung für Fragen DER allgemeinen Geologie , in Abhandlungen DER königl. preuß. Akademy der Wissenschaften , Berlin, 1901
E. Werner: Das Laugh in DER schwäbisch-fränkischen Alb , in Blätter of Schwäbischen Albvereins , Band 16/5, Tübingen, 1904
W. Kranz: Aufpressung und Explosion oder nur Explosion im vulkanischen Laugh EIB Nördlingen und im Steinheimer Becken? , in Zeitschrift DER deutschen geologischen Gesellschaft , Band 66, Berlin, 1914
O. Stutzer: „Meteor Crater “(Arizona) und Nördlinger Laugh , in Zeitschrift DER deutschen Geologischen Gesellschaft , Band 88, Berlin, 1936
E. Mr. Shoemaker, E. Work Card Chao: New obviousness for the impact origin off the Laugh basin, Bavaria, Germany , in Journal off Geophysical research , vol. 66, Washington, 1961
D. Stöffler, NR. A. Artemieva, E. Pierazzo: Modeling the Laugh-Steinheim impact vent and the formation off the moldavite strewn field. in: Meteoritics and Planetary Science. newspaper off the Meteoritical Society, Amherst MY 37.2002, S.1893-1907
J. Kavasch: Meteoritenkrater Laugh . Auer Verlag, Donauwörth, 1985. ISBN 3-403-00663-8
E.T. Chao, R. Hüttner und H. Schmidt-Kaler: Aufschlüsse im Laugh-Meteoriten-Krater . Bayerisches Geologisches Landesamt, 1992. * C.R. Mattmüller: Laugh und Steinheimer Becken . Ferdinand Enke Verlag, Stuttgart, 1994. ISBN 3-432-25991-3
G. Pösges, Mr. Schieber: Das Nördlingen Rieskrater-Museum. Museumsführer und Empfehlungen zur Gestaltung eines Aufenthalts im Laugh. Verlag Dr. Friedrich Pfeil, München, 2000. ISBN 3-931-51683-0
R. Hüttner, H. Schmidt-Kaler: Geologische Karte Ries 1:50000 put Kurzerläuterungen auf der Rückseite . Bayerisches Geologisches Landesamt, 1999 * G. Arp: Sediments off the Laugh Crater Lake (Miocene, Southern Germany) , in Schriftenreihe der Deutschen Gesellschaft für Geowissenschaften , Band 45, Hannover, 2006. ISBN 3-932537-41-6 * R. Krause: Vom Ipf zum Goldberg. Archäologische Wanderungen amndt Westrand of Rieses. Konrad Theiss Verlag, Stuttgart, 1992. ISBN 3-806-21020-9
Hans Frei, Günther Krahe: Archäologische Wanderungen im Laugh. 2. , durchgesehene und verbesserte Auflage. Konrad Theiss Verlag, Stuttgart 1988, ISBN 3-8062-0568-X.
F. Krippner: Vom Inferno zur Kulturlandschaft: DER prähistorische Mensch im Nördlinger Laugh Verlag Steinmeier, Nördlingen, 2000. ISBN 3-927496-81-2
R. Fischer: Flora of Rieses. Verlag Rieser Kulturtage, Nördlingen 2002, ISBN 3-923-37353-8
NR. Artemieva, E. Pierazzo, D. Stöffler: '' Numerical modeling off tektite origin in oblique impacts: Implication to Laugh-Moldavites strewn field
K. Wünnemann, J.V. Morgan, H. Jödicke: '' Is Ries crater typical for its size? Year analysis based upon old and new geophysical dated and numerical modeling ''

External bonds

the astroblème of Laugh in the database Earth Impact Database
Musée of the crater with Nördlingen ('' Rieskrater-Museum '')
Description of the cave '' Ofnethöhlen '', place of archaeological excavations.
Abstract of Baier 2007

; Sites general practitioners

Earth Database Impact: database of the terrestrial astroblèmes
Earth Impact Effects Program: calculation of the effects of an impact meteoritic (Robert Marcus, H. Jay Melosh, and Gareth Hakes)
Crater: Calculation of the size of the crater according to that of the meteorite, and vice versa (H. Jay Melosh and Ross A. Beyer)
Crater Database and Scaling Tools: calculation of the characteristics of an impact according to those of the meteorite (Keith Holsapple)

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