Pebbles from the Rhine, moved over hundreds of kilometers, are the raw material for the relief works of Detlef Kleinen. Collecting the pebbles involves walking along the shoreline from milestone to milestone. Current collecting areas are located around Rhine kilometer 450. The raw material is then sorted by size and cross-section, as well as color of the stones.

The design is inspired by dry stone walls in steep vineyard locations and ancient floor mosaics. The rarity of the extremely flat stones limits the number of images. He works on large reliefs for months to years.