Mastering Weathering

Weathering: The Deterioration of Rocks and Minerals

• Weathering is the deterioration of rocks, soils, and minerals through contact with water, atmospheric gases, and biological organisms.

• Weathering processes are divided into physical and chemical weathering.

• Physical weathering involves the breakdown of rocks and soils through mechanical effects and includes freeze-thaw weathering and thermal fracturing.

• Frost weathering is the most important form of physical weathering and is caused by the formation of ice within rock outcrops.

• Chemical weathering involves the chemical reaction of water, atmospheric gases, and biologically produced chemicals with rocks and soils.

• Water is the principal agent of chemical weathering, converting many primary minerals to clay minerals or hydrated oxides via reactions collectively described as hydrolysis.

• Dissolution is the process in which a mineral dissolves completely without producing any new solid substance.

• Carbonate dissolution is an important feature of glacial weathering and affects rocks containing calcium carbonate, such as limestone and chalk.

• Hydrolysis is a form of chemical weathering in which only part of a mineral is taken into solution.

• Carbon dioxide that dissolves in water to form carbonic acid is the most important source of protons, but organic acids are also important natural sources of acidity.

• Living organisms may contribute to mechanical weathering, as well as chemical weathering, and include lichens and mosses.

• Weathering is a crucial part of the rock cycle, and sedimentary rock, formed from the weathering products of older rock, covers 66% of the Earth's continents and much of its ocean floor.Weathering: The Process of Breaking Down Rocks and Minerals

• Weathering is the process of breaking down rocks and minerals.

• Weathering occurs through various chemical, physical, and biological processes.

• Chemical weathering includes dissolution, hydrolysis, oxidation, and hydration.

• Physical weathering includes freeze-thaw cycles, abrasion, and exfoliation.

• Biological weathering includes the release of chelating compounds, carbon dioxide, and organic acids by plants and soil microorganisms.

• Buildings made of stone, brick, or concrete are susceptible to weathering, which can be accelerated in areas affected by acid rain.

• Accelerated building weathering can be a threat to the environment and occupant safety.

• The degree of weathering of a soil can be expressed as the chemical index of alteration.

• Wood can be physically and chemically weathered by hydrolysis and other processes.

• Weathering of non-geological materials occurs through photochemical reactions.

• The process of weathering takes between 100 and 1,000 years.

• Paleosols are fossil soils that can be identified in formations as old as Archean.