Southern Germany, Miocene // Around 14.8 million years ago, a cosmic impact occurred in the heart of southern Germany when a huge asteroid with a diameter of around 1.5 kilometres crashed into the earth. This impact caused a dramatic shock wave that shook the subsurface of the area that is now the Swabian-Franconian Jura and threw huge amounts of material into the atmosphere. Today, the impact rock suevite - our rock of the year 2024 - can be found in and around the crater.

"In the middle of Germany, we find one of the best-preserved impact craters in the world - this is a special feature that we want to highlight by nominating suevite as Rock of the Year," says Dr Manuel Lapp, spokesperson for the expert committee. The Professional Association of German Geoscientists has nominated suevite as Rock of the Year 2024. Since 2007, the BDG has been publicising the Rock of the Year to the general public, thus drawing attention to the importance of geosciences and rocks in everyday life.

Occurrence and use

The name suevite goes back to the first description in the Nördlinger Ries in 1919, which is derived from the Latin suevia for Swabia, meaning "Swabian stone". It was not until the 1960s that the formation of the Ries crater and thus also that of the suevite could be explained by an impact, through the detection of minerals contained in the suevite, which only form under extremely high pressures and temperatures. Nowadays, the name suevite is used worldwide for rocks formed by an impact.

Suevite is easy to work and was therefore used as a building stone by the Romans. A well-known example from later times is St George's Church in Nördlingen, completed in 1505, with its 90 metre high "Daniel" tower. The Nördlingen town wall and many prestigious buildings in the town are also made of suevite. Supra-regional examples of its use are mainly known from the turn of the 20th century: the Oberpostdirektion Grottenau in Augsburg (1908), the branch office of the Federal Railway Office in Munich (1916), the Royal Bavarian Post Office at the Ostbahnhof in Munich (approx. 1910), the main telegraph office in Berlin (1916) and the "Specks Hof" exhibition centre in Leipzig (1909). Suevite is still mined today in two quarries for the production of trass cement.

Rock of the year 2024

The presentation and naming in 2024 will take place in cooperation with the UNESCO Global Geopark Ries, the RiesKraterMuseum in Nördlingen, Märker Zement GmbH, the Bavarian Industrial Association for Building Materials, Stones and Earth (BIV), the Senckenberg Natural History Collections Dresden, as well as the Bavarian Geological Service in the State Office for the Environment (LfU) and Schwenk Zement GmbH & Co. KG. Events and publications are organised throughout the year to inform the public about the selected rock, its geology, its function in the natural environment, its use and how it is extracted.

Events for this year's Rock of the Year will be announced on the BDG website.

Ellen Mallas

BDG Professional Association of German Geoscientists

The Rock of the Year is chosen annually by the BDG, the Professional Association of German Geoscientists, and is intended to draw attention to rocks that are important because of their geological formation or their economic use.

In 2023 it will be greywacke.

Never heard of it? You're not alone, because this rock is relatively unspectacular and little known. But it is impossible to imagine our everyday life without it. You probably know the term "WACKEr stones" from the fairy tale "The Wolf and the Seven Little Kids" by the Brothers Grimm. A wacker stone is a gravel or paving stone made of greywacke. These were sewn into the belly of the fiend after the little goats he had eaten had been freed, and they pulled him into the well in which he finally drowned. So far, so good!

The german term "Grauwacke" originally comes from the Harz mountains and has been used by the miners there since at least 1780 for a grey-greenish, very solid rock. From the German language, the term found its way into all European languages: e.g. English: greywacke, Portuguese: grauvaque.

Greywacke is often used as paving and masonry stones because of its durability, but it is also used as crushed stone, chippings and concrete aggregates. So if you stroll through an old town or go on holiday by train, you are likely to have greywacke under your shoes or the train tracks.

But how was this inconspicuous rock formed?

Greywacke was formed in the sea. The material for it came from rivers that transported it from the mountains and deposited it under water on the flat continental shelf. If these deposits began to slide, for example due to an earthquake or the exceeding of a critical slope angle, the material shifted in a gigantic turbidity current up to 100 km into deeper water. In the process, large and heavy components were more likely to be deposited than fine material, which led to the fact that greywackes often have a so-called graded stratification: coarse at the bottom - fine to finely laminated at the top. Geologists like to speak of a bouma sequence. Such a sequence is typical for greywackes and makes them so varied. Fossils, however, are rather rarely found in it.

There is no greywacke in the UNESCO Global Geopark Thuringia Inselsberg - Drei Gleichen. The nearest occurrences are in the Thuringian Slate Mountains, in the Harz Mountains and in Lusatia. In total, greywacke is mined in 21 German quarries for a wide variety of uses.