1. Physical Weathering:
* Temperature Changes: Extreme temperature swings between day and night cause the rock to expand and contract, eventually leading to cracks and fractures. This is known as thermal stress weathering.
* Freezing and Thawing: Water seeps into the cracks, freezes, and expands, putting pressure on the rock. This can cause the rock to break apart, a process called frost wedging.
* Abrasion: Wind, rain, and running water carry sand and other particles that collide with the rock, chipping away at its surface.
* Biological Weathering: Plant roots can grow into cracks and exert pressure, breaking the rock. Animals like burrowing rodents can also contribute to physical weathering.
2. Chemical Weathering:
* Oxidation: Iron minerals in the rock react with oxygen, forming iron oxides (rust), which weakens the rock.
* Hydrolysis: Water reacts with minerals in the rock, breaking them down into new minerals.
* Carbonation: Carbon dioxide dissolved in rainwater forms carbonic acid, which reacts with certain minerals like calcite (found in limestone), dissolving them.
* Acid Rain: Pollutants in the air react with water to form acids, which can accelerate chemical weathering.
3. Erosion:
* Gravity: Gravity pulls weathered rock fragments downhill, contributing to erosion.
* Water: Rain, rivers, and glaciers transport weathered rock fragments away from the original location.
* Wind: Wind can pick up and carry small rock fragments, causing erosion.
The Result:
As the rock undergoes weathering and erosion, it will:
* Break down into smaller pieces: This can be anything from boulders to sand-sized particles.
* Change its composition: The chemical weathering process alters the original mineral composition of the rock.
* Be transported: Weathering products are carried away by wind, water, or gravity, forming new landforms like soils, sediments, and beaches.
Eventually, the igneous rock will be transformed into:
* Sedimentary rock: The weathered fragments get buried, compacted, and cemented together, forming new sedimentary rocks.
* Soil: Weathering and decomposition of organic matter contribute to the formation of soil.
* Landforms: Erosion and deposition of weathered material create landforms like canyons, valleys, and deltas.
Note: The speed of these processes depends on factors like climate, rock type, and the presence of vegetation. Some igneous rocks are more resistant to weathering than others.
