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What is Weathering: breaking down dissolving rocks

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weathering

Weathering describes the breaking down or dissolving of rocks and minerals on the surface of the Earth. Water, ice, acids, salts, plants, animals, and changes in temperature are all agents of weathering.

Riesling Cave

For upon |Weathering is the breaking down or dissolving of rocks and minerals on Earth’s surface. Once a rock has been broken down, a process called erosion transports the bits of rock and minerals away. Water, acids, salt, plants, animals, and changes in temperature are all agents of weathering and erosion. All went to work on this ancient mural, eroding on the wall of Riesling Cave in Upper Mustang, Nepal.

Farmer

As it smoothes rough, sharp rock surfaces, weathering, and erosion are often the first steps in the production of soils. Tiny bits of weathered minerals mix with plants, animal remains, fungi, bacteria, and other organisms. Weathered materials from a collection of rocks are richer in mineral diversity and contribute to more fertile soil, like this garden outside the Wolong Nature Reserve, China.

Weathered Rock

Mechanical weathering, also called physical weathering and disaggregation, causes rocks to crumble. This boulder overlooking the San Andres Mountains in New Mexico was split by the process of cryo fracturing, in which water freezes and expands, working to wedge the rock open.

Sugarloaf

Bornhardts like Sugarloaf Mountain overlooking Rio de Janeiro, Brazil, are one of the most dramatic features formed by mechanical weathering.

Honeycomb Weathering

Haloclasty, which produces this distinctive honeycomb pattern in coastal areas, describes mechanical weathering caused by salt crystals wearing away rock.

Banyan in Angkor

Trees, like this banyan in Angkor Wat, Cambodia, can slowly weather stone by vines and roots expanding in and around rocks.

Bioweathering

Other organisms including fungi and animals that tunnel underground, can contribute to weathering by constantly rubbing and carving soil.

Carlsbad Caverns

Chemical weathering changes the molecular structure of rocks and soil. For instance, carbon dioxide from the air or soil sometimes combines with water in a process called carbonation. Carbonation is largely responsible for the enormous limestone caves of Carlsbad Caverns, New Mexico.

Karst

Sometimes, chemical weathering dissolves large portions of limestone or other rock on the surface of the Earth to form a landscape called karst. In Shilin, China, hundreds of slender, sharp towers of weathered limestone rise from the karst landscape.

Chemical Weathering

Materials that contain iron turn to rust in a chemical weathering process called oxidation.

Wave Rock

Hydration and hydrolysis, chemical weathering processes involving rocks interacting with water, contribute to flared slopes, sometimes nicknamed “wave rocks.” Their c-shape is largely a result of subsurface weathering, in which hydration and hydrolysis decompose rocks beneath the landscape’s surface.

Lichen

Bacteria and lichen, like those seen here, can chemically weather rock to access nutrients such as magnesium or potassium.

Leshan Giant Buddha

Weathering is a natural process, but human activities can speed it up. The blackened nose on China’s Leshan Giant Buddha is largely a result of acid rain, which discolors as well as weathers stone.

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