Also known as the “Astrobleme Rochechouart-Chassenon”
The Rochechouart meteorite is one of the 15 largest to hit the earth
This was not some insignificant event. The meterorite that hit between Pressignac and present day Rochechouart, at a place called “La Judie” (Pressignac) is reputedly part of one of the 15 largest ever to hit the earth (source: museum Paul Pellas, Rochechouart).
Geophysicists including David Rowley (University of Chicago), John Spray (University of New Brunswick) Simon Kelley (Open University) have determined that as it fell, the meterorite split into several pieces impacting between La Judie (Presignac) & Babaudus (Rochechouart) and other areas in Europe, Manicouagan in northern Quebec, Saint Martin in Manitoba, Obolon’ in the Ukraine, and the Red Wing crater in North Dakota (according to information drawn from Wikipedia).
In 1969 Scientific research (F. Kraut) in the region advanced a theory of a meteorite which hit about 214 million years ago at the end of the Triassic age (some 120 million years before Yucatan). It was about a mile wideor 1.5km in diameter and weighed some 6,000 million tons and hit at a speed of 20 km a second with an energy some 14 million times that of the Hiroshima bomb. A crater from this “astrobleme” – now believed to be between 40 – 50 kilometres wide – was formed within 42 seconds of impact, vaporising some 8 cubic miles of the earth’s crust and vitrifying a further 42 cubic miles. All life within 300 miles of the impact at modern-day Rochechouart was wiped out.
Source: Association Pierre de la Lune. Graphic courtesy of J-P Poursac and the Comité des Usagers du Territoire de la Météorite.
In the intervening 200 million years the crater shape has been gradually worn down leaving scientists and geologists with one of the few accessible crater beds in the world where it is possible to see the progressive effects of impact shock on the surrounding rock. Specialists from NASA came to the site to gather information before the Apollo missions (and not just to sample the French wine?). The river that runs at the base of the chateau at Rochechouart runs in the socle, the crater bed, of the meteorite. Of the meterorite itself, there is no trace, since it “sublimed” on impact – all that remains are trace elements. Of the impact crater too, there is no remaining trace since this too has eroded. What remains are traces of the shock-wave and the incredibly high temperatures reached.
The impact breccia formed by the impact has furnished building materials to the local area over the millennia. Much of Rochechouart castle and the church, The Roman Baths at Chassenon are made of it; the church and castle at Rochechouart are; the church in Pressignac; and many of the local old buildings – including parts of our gite (see picture).
A good, readable article exists on Wikipedia, see: http://en.wikipedia.org/wiki/Rochechouart_crater
Chateau at Rochechouart, at the foot of which (out of shot) is believed to be the socle, or meteorite bed.
A building slab used in the Gite at La Croix Spa, showing very clearly the concretions in the stone, typical of impact breccia of the Rochechouart meteorite. (Note the colour variations (less iron content?) with the stone at Rochechouart which was far closer to the epicenter of the impact. La Croix is about 8km out from this).
My diagram shows the approximate “ripple” effect geologists believe to have occurred around Rochechouart following the meteorite’s impact.
The photo taken from Pressignac overlooking Rochechouart (i.e. West to East) certainly demonstrates a very visible “bowl”. (Rochechouart is about 8km away and is at a lower elevation from Pressignac).
There is an amazing quarry at Champagnac where the vitrified rock (i.e. beneath the impact and not vaporised or blown into the atmosphere) and the fallout that fell back on top can clearly be seen as two separate layers one on top of the other.
(Photo Courtesy of J-P Poursac Comité des Usagers du Territoire de la Météorite)
On 18th September 2008 a national natural reserve for the “Astrobleme Rochechouart-Chassenon” was created with the aim of preserving the landscape as well as selective and careful promotion of its scientific and cultural interest.
A museum to the meteorite is found in Rochechouart from which much of the above information is drawn.
“Espace Meteorite Paul Pellas”, 16 Rue Jean Parvy, Rochechouart.
Linguists may be interested to note that the name “Rochechouart” does not mean “The Rock that fell” (Roche, échoué) although the accident of language and ancient history seems startling. In fact the name came about in far more mundane ways. In mediaeval times, “Chouart” was the land-owner and the rock was his. “Chouart’s Rock”.
Publisher: La Croix Spa
“The Rochechouart Meteorite” by Richard Martin is licensed under a Creative Commons Attribution-No Derivative Works 2.0 UK: England & Wales License.
Based on a work at www.espacemeteorite.com.
Permissions beyond the scope of this license may be available at http://www.lacroixspa.com.
The Rochechouart metorite is one of many attractions for people of all tastes visiting the Charente, Vienne or Dordogne. From visiting geologists to cyclists who wish to mountain-bike around the meteorite crater trail. Rochaechouart really was at the very epicentre of this cataclysmic ancient meterorite impact and from Pressignac you can see across 22 kilometers from crater rim to crater rim from Pressignac to Etagnac and St. Junien. Local buildings, including Rochechouart chateau, church and Pressignac Church and even stone in our gites are made from the impact breccia of the Rochechouart meterorite. For this and many other activities, have a great holiday in our region of Southwest France.