1. Weathering:
* Physical Weathering: This is the mechanical breakdown of rocks and minerals into smaller pieces. It's caused by things like:
* Frost wedging: Water freezes in cracks, expands, and breaks the rock.
* Abrasion: Rocks and sand are carried by wind or water, grinding against other rocks.
* Thermal expansion and contraction: Rapid temperature changes cause rocks to expand and contract, leading to fracturing.
* Chemical Weathering: This is the breakdown of rocks through chemical reactions. Examples include:
* Oxidation: Iron in rocks reacts with oxygen, forming rust and weakening the rock.
* Dissolution: Acidic rainwater dissolves certain types of rocks, like limestone.
* Hydrolysis: Water reacts with minerals in rocks, changing their composition.
2. Erosion:
* This is the process of moving weathered material from one place to another. The major agents of erosion are:
* Water: Rivers, streams, and ocean waves carry away sediments.
* Wind: Wind can pick up and transport sand and dust, causing erosion.
* Ice: Glaciers carve out valleys and transport rocks and soil.
* Gravity: Gravity pulls rocks and soil downhill, causing landslides and soil creep.
Other forces:
* Plant roots: As roots grow, they can crack and break rocks.
* Animals: Burrowing animals can loosen and transport soil.
* Human activities: Mining, construction, and agriculture can all contribute to erosion and weathering.
These forces work together to constantly reshape the Earth's surface, creating mountains, valleys, canyons, and other landforms.
