Wetterung

Wetterung, in geology, is the breakdown and alteration of rocks and minerals at or near Earth's surface, driven by physical, chemical, and biological processes. Unlike erosion, weathering acts in place and does not involve external transport of material.

Physical or mechanical Wetterung includes frost wedging, thermal expansion and contraction, exfoliation due to unloading, and salt crystallization, as well as biological actions such as root growth and microbial activity that pry rocks apart.

Chemical Wetterung involves reactions with water and atmospheric gases, including hydrolysis, hydration, dissolution, oxidation, and carbonation, which change mineral structures and reduce strength.

Rates and patterns of weathering depend on climate, rock properties, hydrology, topography, time, and structural features such as joints and fractures. In general, chemical weathering dominates in warm, moist climates, while physical weathering is more important in cold or arid environments, though both operate together.

Outcomes include soil formation (pedogenesis), the creation of regolith, the release of soluble ions into groundwater, and alteration of mineral assemblages. Weathering contributes to landscape evolution and can produce features such as karst in soluble rocks.

Examples: Granite commonly weatheres to clay minerals and secondary oxides; limestone dissolves by carbonic acid to form caves and sinkholes; basalt can weather to clays and iron oxides.

The term Wetterung is used in German-language geology; in English, the equivalent concept is weathering.