La machine à trier les cailloux

Soit un panel de cailloux prélevés dans le lit d'un torrent de montagne, le Jller, affluent du Danube en Allemagne pas loin de la ville d'Ulm. Deux grandes catégories ont été identifiées : la cailloux provenant de l'érosion des torrents et ceux, plus anciens, du frottement des glaciers. Les textures, sombres, claires ou zébrées de ces cailloux ainsi que leur forme et aspect global ont été modélisés et ont donc une empreinte générale que la machine arrive à reconnaître.

Cette installation a été réalisée par Prokop Bartoníček (CZ) et Benjamin Maus (DE).

Jller is part of an ongoing research project in the fields of industrial automation and historical geology. It is an apparatus, that sorts pebbles from a specific river by their geologic age. The stones were taken from the stream bed of the German river Jller, shortly before it merges with the Danube, close to the city of Ulm. The machine and its performance is the first manifestation of this research.
A set of pebbles from the Jller are placed on the 2x4 meter platform of the machine, which automatically analyzes the stones in order to then sort them. The sorting process happens in two steps: Intermediate, pre-sorted patterns are formed first, to make space for the final, ordered alignment of stones, defined by type and age. Starting from an arbitrary set of stones, this process renders the inherent history of the river visible.
The history, origin and path from each stone found in a river is specific to the location, as every river has a different composition of rock types. The origin of those stones is well documented. For instance, the ones from the river Jller derive from two origins. Some come from rocks, that are the result of erosions in the Alps and are carried in from smaller rivers. Other stones have been ground and transported by glaciers that either still exist, or existed in the ice ages. As the Alps and flats, that were once covered by glaciers, have shifted, even deeper rock-layers were moved and as a result, stones from many geologic periods make their way into a river.
When the history of a river is known, the type of stone can be directly related to its geological age. One very common sedimentary rock is the dark grey limestone from the Triassic period (225 million years ago). It was formed from the layers of sediments in the primeval ocean. Granodiorite, on the other hand, is an igneous rock of volcanic origin from the Tertiary Period (30 to 40 million years ago). Between those types there is a variety of metamorphic rocks, created by the transformation of existing rock types through the influence of temperature and pressure over time. Furthermore, a small amount of pebbles are formed by non-rock materials like red brick or slag, that have their origin in the Anthropocene.
Most of the time, stones do not appear as a singular uniform material, but as a composition of different, laminated or layered materials. A prominent example of his are the white lines of lime in grey pebbles.
Jller was presented as part of Ignorance, a collaborative exhibition of German artist Benjamin Maus and Czech artist Prokop Bartoníček.