Everyday we witness weathering at work: from cracks in sidewalks to beaches covered with sand. Weathering occurs when forces erode rocks, soils and minerals from their position underground or surface up by wear-and-tear erosion.
Water plays an essential part in weathering. Liquid water seeping into cracks and crevices can cause rocks to expand as it seeps in, this process known as mechanical weathering or abrasion.
Physical weathering refers to the process of breaking apart rock formations through physical forces like pressure, warm temperatures, water or ice. Abrasion may also play a part in this process – when one rock bumps against another. Rainwater often enters cracks in rocks before freezing in colder environments and acts like a wedge to split them apart; such weathering phenomena is common in arid and mountainous regions and at high elevations where rainwater seeps through cracks into cracks to form wedges between stones that split apart their layers causing cracks between fractured surfaces which creates wedges in rocks causing them to split apart completely resulting in piles similar to what Figure 8.5 shows as shown from falling fragments falling off steep mountainsides or cliff faces creating piles of rock fragments called “talus piles”.
Animal and plant movement is another source of physical weathering, such as tree roots forcing themselves into even small cracks in rocks to widen and eventually fracture them apart. Moles may tunnel underground, further contributing to physical weathering; humans too contribute by digging or otherwise altering the ground surface.
Chemical weathering alters the molecular structures of rocks and minerals, softening and making them more easily eroded – it’s even responsible for creating beautiful caves and rock formations around the world!
Carbonation, hydration, oxidation and hydrolysis are forms of chemical weathering which occur when surface and soil water interact with rocks causing the minerals within to decompose or dissolve, or change shape over time.
Carbon dioxide in the air combined with rainwater forms a weak acid which dissolves limestone, thus creating caves like Carlsbad Caverns in New Mexico.
Chemical weathering can also occur from chemicals in the atmosphere. When coal, fossil fuels and natural gas burn they release sulfuric and nitric acids that combine with rainwater to form acid rain; this acid rain erodes rocks and soil while also leaving acid spots that etch and crack rocks.
Biological weathering refers to the physical and chemical actions taken by plants, animals, microorganisms and humans to remove ions and minerals from the environment through growth and movement of organisms in an ecosystem, with water and oxygen acting as catalysts in speeding this process up.
Biological weathering involves the physical actions of animals like ants, rodents, earthworms and other creatures such as burrowing ants, burrowing rodents and digging animals who use burrowing, hammering and digging as methods of bioweathering. Their activities expose rock fragments to water and air which makes them vulnerable to both abrasion and chemical weathering processes.
Plants can help weather rocks by growing into cracks on their surfaces and extracting nutrients to break down rocks over time.
Weathering is one of the key natural processes on Earth that produces one of its most precious natural resources–soil. Weathering works by weakening and disintegrating rocks into smaller particles which can then be dispersed through wind or other forces to form soil deposits.
Human activities can accelerate the weathering process. For instance, burning fossil fuels such as coal, oil and gas releases chemicals into the atmosphere that can combine with sunlight and rainwater to form acids which fall as acid rain on Earth, damaging limestone, marble and other types of rock formations.
Worms and termites, for instance, contribute significantly to chemical weathering through digging holes and building passageways and galleries in rocks that become cavities filled with sand, dust or other materials. Furthermore, biological weathering takes place when trees’ mycorrhizal fungi release inorganic nutrients from minerals like apatite or biotite to support tree growth; scientists are still learning more about the impact that microbes have on mineral stability and weathering processes.