Jäännöskerros

Jäännöskerros, often translated as residual layer, is a geological term referring to a layer of material that remains in situ after the weathering and decomposition of an underlying rock mass. This layer is formed by the breakdown of the parent rock through physical and chemical processes, such as hydrolysis, oxidation, and carbonation, without significant transport or deposition of the weathered material. The composition and properties of the jäännöskerros are directly inherited from the original rock.

The formation of a jäännöskerros is a slow process occurring over geological timescales. It is typically found in areas where erosion has not been significant enough to remove the weathered material, allowing it to accumulate directly on top of the unweathered bedrock. The thickness of the jäännöskerros can vary greatly depending on the rock type, climate, and duration of weathering. For instance, granitic rocks may weather to form thick layers of clay-rich residual soil, while more resistant rocks might only develop a thin jäännöskerros.

Jäännöskerros plays an important role in soil formation and landscape evolution. It can act as a substrate for vegetation and influence hydrological processes. Understanding the properties of the jäännöskerros is crucial in various fields, including engineering geology, environmental science, and resource exploration, as its characteristics can affect foundation stability, groundwater flow, and the distribution of mineral deposits. The term is particularly relevant in Finnish geological contexts.