Weathering is the decomposition of rocks, soils and their minerals through direct contact with the Earth's atmosphere. Weathering occurs in situ, or with no movement, and thus should not to be confuse
d with erosion, which involves the movement and disintegration of rocks and minerals by agents such as water, ice, wind and gravity.
The mechanical, chemical, or biological action of the atmosphere, hydrometeors, and suspended impurities on the form, color, or constitution of exposed material; to be distinguished from erosion. Mech
anical weathering results from the disintegrating action of high or low temperature, large changes of temperature, frost, or the impact of wind-borne sand or water (e.g., frost action, scouring, etc.). Chemical weathering is due to the chemical action of atmospheric constituents, especially acid impurities, in a moist atmosphere or in rainwater (e.g. corrosion, oxidation, etc.). Biological agents are mainly fungi that attack organic material (e.g., rotting, mildew, etc.).
A friable surface layer, of reduced density, that develops due to small-scale variations of the melting rate of ice in the presence of cryoconite. Short-term measurements of surface lowering are unrel
iable as estimates of surface ablation when there is a weathering crust. The crust may reach a thickness of the order of 100200 mm over several days, only to be removed abruptly by rain or strong winds.