“Jller” is part of an ongoing research project at the intersection of the fields of industrial automation and historical geology. It is an apparatus that sorts pebbles collected from the German river Jller according to their geologic age. The stones were taken from a spot close to the city of Ulm, right before where the Jller meets up with the Danube. After they are laid out on the approximately 2 x 4 meter platform of the machine, the structure of each pebble is automatically analyzed using an image recognition device, and by comparing them against predetermined standard features, their geological ages are estimated. Then, an industrial vacuum gripper does a preliminary sorting of the pebbles while simultaneously creating enough space on the platform, and finally, it lines up the pebbles in a grid according to age and type. As pebbles from rivers have distinct compositions and structures, their origins can be determined with some degree of precision. The stones from the Jller, although their geologic ages vary, consist largely of two groups with different origins: rocks that are the result of erosion in the Alps, and stones that were crushed and transported by the glaciers. The pebbles today carry the accumulated effects of their delicate interaction with the river throughout the years, and this work, while emitting inorganic mechanical sounds, invites us to reflect on their long history.