Geröll

Geröll refers to a geological term for loose, angular fragments of rock that have been dislodged from their parent rock and accumulated. These fragments are typically larger than gravel but smaller than boulders, ranging in size from a few centimeters to several meters in diameter. Geröll is commonly found in areas where rock weathering and erosion are active, such as mountain slopes, scree slopes, and riverbeds.

The formation of geröll is primarily driven by physical weathering processes. These include freeze-thaw cycles, where water seeps into cracks in rocks, freezes, expands, and widens the cracks, eventually breaking off pieces. Thermal expansion and contraction due to temperature fluctuations can also contribute to rock fracturing. Additionally, biological activity, such as root wedging by plants, can exert pressure on rocks and cause them to break.

Once dislodged, these rock fragments accumulate through gravitational processes like rockfalls, landslides, and debris flows. The angular shape of geröll suggests that it has not been transported over long distances, as abrasion during transport would tend to round the fragments. Therefore, the presence of geröll often indicates proximity to its source rock.

Geröll deposits can play a significant role in landscape formation and ecological processes. They can stabilize slopes, provide habitats for certain plant and animal species, and influence hydrological patterns. The study of geröll is important in geology for understanding weathering mechanisms, erosion rates, and the history of geological events.