1. Weathering: This is the breakdown of rocks, soil, and minerals through contact with the Earth's atmosphere, water, and biological organisms.
* Physical weathering: Includes processes like frost wedging (water freezing and expanding in cracks), abrasion (rocks rubbing against each other), and thermal expansion and contraction.
* Chemical weathering: Includes processes like oxidation (rusting), dissolution (rocks dissolving in water), and hydrolysis (water reacting with minerals).
2. Erosion: This is the movement of weathered material from one location to another by agents such as:
* Water: Rivers, rain, glaciers, and ocean waves all carry away rock fragments.
* Wind: Wind can pick up and transport sand and dust, causing erosion.
* Gravity: Gravity causes landslides and rockfalls, moving material downhill.
* Glaciers: These massive ice sheets carve out valleys and transport rock debris.
3. Mass Wasting: This refers to the downslope movement of rock, soil, and regolith due to gravity. Examples include:
* Creep: Slow, gradual downhill movement of soil and rock.
* Slumps: Rotational slides where blocks of material move downhill.
* Rockfalls: Sudden detachment and freefall of rocks.
4. Plate Tectonics: The movement of Earth's tectonic plates can cause mountains to rise and fall, impacting their erosion rates.
5. Biological Activity: Plants and animals can contribute to weathering and erosion. For example, tree roots can break up rocks, and burrowing animals can loosen soil.
These forces work together over millions of years to gradually wear down mountain ranges, eventually creating gentler hills and plains.
