Weathering, or the process of changing rock’s chemical composition over time, is a natural phenomenon caused by both natural forces and human activities. Air pollution caused by burning fossil fuels increases levels of nitrogen oxide and sulfur dioxide in the atmosphere which combine with sunlight and moisture to form acid rain that damages limestone and marble gravestones and renders names or inscriptions on them illegible.
Water
Water in rivers or oceans wears away at rocks while also dissolving minerals, taking their fragments with it as it flows downstream. This process, known as physical weathering, includes processes such as freeze-thaw cycles, abrasion and root expansion.
Most often, weathering occurs naturally; however, sometimes living organisms can help facilitate it. For example, plant roots can penetrate small cracks in rock and form new ones as their roots grow larger; over time this weakens and eventually breaks off pieces of the rock surface.
Once rocks have been broken into smaller pieces, they can be transported by water, wind and glaciers into different locations through erosion – this force was responsible for creating iconic landmarks such as Arizona’s Grand Canyon.
Wind
Wind can cause physical weathering to rocks by depositing sand and silt onto them from windblown storms, while it also erodes them through erosion by blowing on them sand and silt from distant storms, as well as sandblasting them, leading to cracking and breaking apart, known as abrasion. Chemical weathering may occur if salt gets into cracks or holes in rocks before evaporating out to leave behind layers of crystalized salt deposits, making the rock much softer and easier to break apart than otherwise.
Erosion wears away at tall mountains and other landscapes while weathering breaks them down into soils, producing the rocky terrain we see today. Together these forces of erosion and weathering create the rocky landscapes we see today as well as making rocks easier to dig into for building purposes and use during construction projects – which humans can then shape further through human activities. Learn more about three types of weathering at our Rock Cycle Teaching Wiki.
Plants
Plants can contribute to chemical weathering by taking in moisture and other materials from their environment, or breaking down minerals. Symbiotic fungi in tree roots release chemicals that alter the composition and structure of minerals like apatite and biotite; this causes weakening or crumbling in rocks as these changes weaken and break apart their mineral structures.
Chemical weathering occurs when rocks rich in iron are exposed to air, leading them to rust over time – this form of weathering is commonly known as oxidation.
Plants can contribute to physical weathering by expanding cracks in rocks. Tree roots often grow into the cracks of rocks, slowly breaking them apart over time. Animals with tunneling abilities also work to dismantle rocks underground while other animals may trample or scrape rocks aboveground which deteriorates it over time.
Animals
Many animals live in the same areas year round and must adjust to large temperature fluctuations. Animals that don’t hibernate or hibernate during colder temperatures must endure high temperatures while still dealing with harsh winter weather. This may result in heat exhaustion, dehydration and malnutrition for these non-hibernating species.
Animals have long been thought to have the ability to predict weather events; however, most claims relating to this claim are based on folklore rather than scientific research. However, some animals may detect environmental signals indicating changes in barometric or hydrostatic pressure which result in decreases in atmospheric air volume which causes animals to change their behavior – for instance by becoming restless or seeking shelter.
Human Activities
Human activities that aid and speed up weathering include agriculture, mining and quarrying. Air pollution caused by burning fossil fuels can alter atmospheric gas balance and allow acid rain to further weather rocks and soil – this process is known as chemical weathering.
Mechanical weathering such as abrasion is one method used to turn rocks with sharp or jagged edges into smooth and round structures, such as waves crashing onto beaches wear down cobbles and pebbles by friction (abrasion). Plants and animals also help weather rocks through mechanical means – for instance, plant roots exert stress onto rock which weakens it before breaking it apart while burrow digging animals can break apart rocks as they search for food or shelter.
All these weathering processes help form soil. Tiny pieces of various minerals combine together into rich, vibrant soil.