Weathering is the process by which rocks and minerals at Earth’s surface are broken down by water, ice, acids, salts, plants/living things/temperature changes/erosion.
Broken pieces are then distributed through deposition. Examples of such deposition are erosion sculpting the Grand Canyon and Carlsbad Caverns, as well as lichens breaking down limestone in caves.
Physical
Weathering occurs through physical processes, including freeze-thaw cycles and abrasion. These processes break rocks and soil down into smaller particles, leaving behind irregular or more rounded shapes than before they were exposed to weathering, while possibly creating fractures and cracks along their surfaces.
Environment conditions that contribute to this process include high temperatures and frequent temperature fluctuations, which cause mineral composition of rocks to expand and contract at differing rates, creating stress on its outer layers that could eventually wear away and crumble away.
Unloading is another type of physical weathering that occurs when overlying materials are removed through erosion, relieving pressure from an underlying rock surface and leading to its eventual decompression. As more material is removed through erosion, its confining pressure on it decreases and this allows its surrounding confinement pressures to relax allowing its stress points to release their tension causing sheet fracture or exfoliation to take place – particularly prevalent for certain rocks whose minerals react with water molecules.
Chemical
Weathering, or chemical weathering, occurs when minerals in rocks change their physical structures and properties when exposed to water. This natural process may be further accelerated by climate factors like precipitation and warmer temperatures.
Feldspar minerals interact with water to form clay minerals, altering the structure of rock and making it more vulnerable to erosion.
Other examples of chemical weathering include carbonation, when rainwater with an optimal pH level reacts with calcium carbonate from rocks and cliffs; oxidation, when free oxygen reacts with iron minerals present in rainwater to form new minerals such as hematite or limonite; and dissolution, when mineral salts dissolve away into rivers and oceans.
Physical weathering of rocks and soil is crucial to ecosystem health. It determines the availability and quality of nutrients such as nitrogen (N), phosphorus (P), and potassium (K), to plants as well as altering landscape features and creating new landforms.
Biological
Biological weathering involves living organisms such as plants, bacteria and fungi acting together. Plant roots can penetrate cracks to slowly erode rocks over time while lichen can release acids that dissolve minerals to break down rocks into small fragments. Furthermore, animals like burrowing animals such as shrews and moles can dig up rock fragments from deep underground before exposing them to environmental conditions that accelerate weathering processes such as wind, water or chemical weathering processes that accelerate weathering processes – speeding their demise even faster.
Living organisms’ influence on mineral-weathering processes has long been recognized and tentatively modeled, yet often goes overlooked when considering overall rock weathering processes. This type of weathering, known as biological weathering (BW), is enhanced by living organisms through various mechanisms including direct contact at mineral surfaces, secretion of organic acids nearby, or creation of confinement spaces resulting from microorganisms within EPS structures.
Environmental
Weathering is a natural process that breaks down rocks and minerals on Earth’s surface, shaping its landscape in the process. Weathering occurs when rocks and minerals come in contact with external forces such as temperature variations, water flow, wind speeds or biological activity that breaks them down over time.
Weathering of rocks depends on their composition and type. Limestone is more susceptible than granite to weathering; high temperatures and rainfall accelerate its rate.
Chemical weathering occurs as the result of natural chemical reactions that change the composition of rocks over time, including interlocking silicate grains in fresh granite decaying along crystal boundaries to produce fissures and pores; similarly karst formations which give rise to caves and sinkholes also display this kind of weathering phenomenon. Other forms include iron being converted to rust by oxygen (oxidation), or water percolating through rocks to expand and crack them over time.