1. Weathering:
* Physical Weathering: This is the mechanical breakdown of the granite.
* Frost Wedging: Water seeps into cracks in the granite, freezes, expands, and widens the cracks.
* Thermal Stress: Rapid temperature changes cause the granite to expand and contract, leading to cracks and eventual breakdown.
* Abrasion: Wind, rain, and ice carrying sand and other particles abrade the granite surface, wearing it down.
* Chemical Weathering: This is the breakdown of the granite through chemical reactions.
* Hydrolysis: Water reacts with the minerals in granite, breaking them down.
* Oxidation: Oxygen reacts with iron-bearing minerals in the granite, forming rust (iron oxide) and weakening the rock.
* Biological Weathering: Plants can grow in cracks, their roots widening them, and lichen can produce acids that chemically weather the granite.
2. Erosion:
* Gravity: Weathering weakens the granite, making it susceptible to gravity. Rockfalls, landslides, and debris flows move granite fragments downhill.
* Water: Rainwater, rivers, and glaciers carry away weathered granite fragments, transporting them further from the mountain.
* Wind: Wind can carry fine sand particles, abrading the granite and moving smaller fragments.
3. Transportation:
* Rivers: Granite fragments are carried by rivers, getting rounded and smoothed by abrasion during the journey. The smaller fragments are carried further downstream.
* Glaciers: Giant ice sheets can carve out valleys and carry massive amounts of granite, depositing it as glacial till.
* Wind: Wind can carry sand-sized granite fragments, depositing them as sand dunes.
4. Deposition:
* Beaches: Rivers and waves deposit granite fragments on beaches, where they are further rounded and smoothed by wave action.
* Seafloor: Waves, currents, and submarine landslides carry granite fragments to the seafloor, where they eventually become part of the sediment.
5. Transformation:
* Grain Size: As granite is weathered and transported, the grain size decreases. Large boulders become cobbles, pebbles, sand, and eventually, fine silt.
* Shape: Granite fragments become more rounded and smooth as they are abraded during transport.
* Mineral Composition: The chemical weathering of granite alters its mineral composition. Some minerals are dissolved, while others may be altered or replaced.
Ultimately, the granite that reaches the sea has undergone a dramatic transformation from its original state in the mountain. It has been broken down into smaller pieces, rounded, smoothed, and may have undergone changes in its mineral composition. This process, called the rock cycle, is a continuous cycle of weathering, erosion, transportation, and deposition that shapes our planet's surface.
