Weathering:
* Physical Weathering:
* Frost Wedging: Water seeps into cracks, freezes, expands, and widens the cracks over time.
* Thermal Expansion and Contraction: Daily temperature swings cause rocks to expand and contract, leading to fracturing.
* Abrasion: Wind-borne sand and rock particles scour the surface, chipping away at the mountain.
* Chemical Weathering:
* Dissolution: Water, especially acidic rainwater, dissolves certain rocks like limestone.
* Oxidation: Oxygen reacts with minerals in rocks, causing them to weaken and break down.
* Hydrolysis: Water reacts with minerals, breaking them down into new compounds.
Erosion:
* Water Erosion:
* Rivers and Streams: Water flows downhill, carrying away sediment and carving channels.
* Glaciers: Massive sheets of ice carve valleys and transport rock debris.
* Rain: Rainwater can create gullies and transport sediment.
* Wind Erosion: Wind picks up loose sediment and can sandblast mountain surfaces.
* Gravity: Landslides, rockfalls, and creep move rock and soil downhill, sculpting the mountain's slopes.
Other Processes:
* Biological Weathering: Plants, lichens, and bacteria can break down rock through their growth and chemical processes.
* Plate Tectonics: As tectonic plates collide, mountains rise, but they also erode at a faster rate due to the increased exposure to weathering and erosion forces.
These processes work together, often in a cycle, to constantly reshape the landscape. The exact balance between the forces that build mountains (plate tectonics) and those that wear them down (weathering and erosion) determine the overall shape and age of a mountain range.
