The Ries Meteorite Crater

OUGSME field trip to the Ries Crater on Saturday the 21^st of January 2005 in connection with the AGM

The Ries crater is with a diameter of 25 km the largest and best reserved meteorite crater on earth. It was formed about 15 million years ago by the impact of an asteroid presumably measuring 1 km in diameter.

Stop 1 - Ebermergen

This is an intensely quarried, allochtonous (impact ejecta) mega-block of Kimmeridgian limestoe where the deformation and shattering of the rock fabric caused during transport and deposition can be clearly seen. The ruins of a fortification during the 15^th century are still visible on the top of the block.

Stop 2 - Ries Crater Museum Nördlingen

Stop 3 - Altenbürg Quarry

In the accommodation left between two ("parautochtonous") impact ejecta megablocks (of Malmian limestone) suevite has settled in.

The suevite is greatly weathered and yellow from clay minerals.(The yellow colour is more evident in the dry part at the arrow on the picture above than on the wet surface on the picture to the left, where the composition shows better).

Suevite means „Swabian stone“ (The Romans called the celtic tribe inhabiting Schwaben the ‘Sueven’).

More about suevites.

Stop 4 - Meyr's Cellar, Nördlingen

Crystalline Breccia. Many different types of brecciated crystalline fragments (from the crystalline basement) are mixed together -> polymict cristalline breccia.

Stop 5 - Wallersteiner Felsen

Wallerstein is a small town situated within the main crater and built around the cliffs of the inner ring, which were formed by the rebound of the crystalline basment rocks.

Exposure of freshwater calcarious deposits (around an artesian well about 14 — 13 Ma) indicate the early water-level of the crater lake and in good visibility, the viewing point on top of the cliffs offers an excellent view across the main crater.