Weathering and erosion are essential processes that shape Earth’s landscape. Discover how they work together to form landforms like canyons, beaches and gorges.
Chemical weathering refers to processes involving the interaction of water with minerals, including hydration (transforming them), hydrolysis and oxidation. Over time these processes wear away rocks and minerals that come into contact with water such as limestone and granite.
Water can have devastating effects on weathering and erosion processes, softening and breaking apart solid rock surfaces while simultaneously transporting pieces elsewhere by wind, gravity or moving waters.
Mechanical weathering does not alter the chemical makeup of rocks; however, other forces such as solar heating and cooling, frost or crystal wedging, acid rain and air corroding iron could also contribute to breaking them apart in this manner.
When flowing water reaches flatter land, its flow slows, causing sediment-laden currents to settle on the land surface and eventually create features such as deltas or alluvial fans. As it continues, more material may settle along its route forming beaches, spits, shoals or making the sea saltier through carrying away minerals into it.
Wind erosion occurs when airborne particles transport sand, silt and other materials to new locations. This phenomenon can often be found in desert areas as winds create massive sand dunes; or polish rocks and cliffs creating an eroded surface susceptible to further water-induced erosion.
Wind erosion depends on weather conditions and particle sizes; moisture-soaked grounds tend to become heavier and thus less vulnerable to being carried off by the wind. Furthermore, larger particles tend to be more likely to be eroded than their smaller counterparts.
Wind erosion involves several processes such as surface creep, saltation and attrition. Surface creep involves particles rolling, bumping and skipping over soil surfaces while surface saltation involves transport of medium sized particles up to several kilometers distances away. Attrition breaks particles apart into smaller pieces that are then carried off by wind erosion.
Plants and animals cause physical weathering by breaking rocks into smaller pieces; chemical weathering involves dissolving minerals so they can be taken up by soil.
Deposition begins once wind, water, ice or gravity lose their energy to carry away their load of eroded material and stop carrying its load of erosional forces such as wind or gravity. Deposition is the act of depositing sediment in new locations – creating deltas at the ends of streams; creating sandy beaches along ocean shorelines; or leaving gravel deposits along rivers.
Erosion and weathering continuously alter Earth’s landscape, both destructively (such as rockfalls or mudslides that kill people and destroy buildings) as well as positively, by providing fertile soil where previously there was none and supporting numerous forms of life. Therefore, understanding how weathering and erosion interact can help us protect ourselves against their adverse effects.
Chemical weathering occurs when minerals in rocks react with water. For instance, rocks containing iron may oxidize, making it easier for physical forces to break them apart and break apart the rock mass itself.
Chemicals in the air can also accelerate weathering. Burning fossil fuels such as coal, oil and natural gas releases sulfur, nitrogen and carbon into the atmosphere, mixing with water vapor to form acids which eventually fall back down as raindrops – creating acid rain which attacks limestone, marble and other types of stone quickly, even rendering gravestone inscriptions unreadable.
Chemical weathering is more likely to occur in environments with abundant moisture, such as rain forests or near oceans. Furthermore, warmer climates tend to experience greater chemical weathering reactions as the chemistry of weathering reactions changes with temperature.