Types of Weathering

• Physical weathering, also known as mechanical weathering, is the disintegration of rocks, breaking them into smaller pieces due to any force, without altering its composition.
• Frost wedging is a process in physical weathering where repeated freezing and thawing of water found in the cracks of rocks called joints pushes the rock to the breaking point.
• Salt crystal growth is a process in physical weathering where enough build-up of salt crystals left behind in pore spaces or cracks of rocks as water evaporates can cause the rock to expand, and eventually break apart.
• Abrasion is a process in physical weathering where rocks are worn away by colliding particles.
• Exfoliation is a process in physical weathering where reduced pressure on igneous rock causes it to expand and allows slabs of outer rock to break off in layers.
• Biological activity, such as the application of pressure on rocks by animals, microbes and plants, is a process in mechanical weathering.
• Chemical weathering is the decomposition of rocks involving chemical reactions causing change in their chemical makeup as influenced by low pressure, low temperature, and the water and oxygen-rich nature of the Earth's surface.
• Dissolution/carbonation is a process in chemical weathering where dissociation of molecules into ions, such as the dissolution of calcite and salt, removes rock by acidic rainwater in solution especially dissolved CO2-containing rainwater.
• Oxidation is a process in chemical weathering where rock breakdown by oxygen and water, often giving a rusty-colored weathered surface to iron-rich rocks.
• Hydrolysis is a process in chemical weathering where acidic water breakdown of rock produces clay and soluble salts.
• Biological activity, such as the production of organic acids by plant roots that help dissolve minerals in rocks or microorganisms that consume minerals on rocks, is a process in chemical weathering.
• Climate affects the type, extent and rate at which weathering takes place, with warm climates affecting by chemical weathering while cold climates affecting by physical weathering.
• Mineral composition in a rock may readily react with acids, water or oxygen, for example limestone can be severely acted upon by mild acidic rainwater while granite which contains silica remains unaffected by such agents.
• The susceptibility of minerals to weathering roughly follows the inverse of the order of crystallization of minerals in the Bowen's reaction series, with olivine which crystallizes first being the least resistant and quartz which crystallizes last being the most resistant.
• Rock structure, such as soft (amorphous) and those highly fractured/jointed rocks, affects the ease of weathering.
• Topography - physical weathering occurring more quickly on a steep slope than on a gentle one, and chemical weathering being enhanced on a gentle slope, where water may stay longer in contact with the rocks.
• Time - duration of time for which a rock is exposed to weather determines the extent of weathering.
• Physical Weathering and Chemical Weathering are two main types of weathering.
• Physical Weathering (Mechanical Weathering) - the disintegration of rocks breaking into smaller pieces due to any force (natural or anthropogenic) without altering its composition (Guzman et al., 2016)
• The processes of physical weathering include: frost wedging, salt crystal growth, abrasion, exfoliation, and biological activity.
• The processes of chemical weathering include: dissolution/ carbonation, oxidation, hydrolysis, and biological activity.
• Factors affecting weathering: climate, mineral composition, rock structure, topography, and time.