1. Weathering and Erosion:
* Mechanical Weathering: Physical forces break the igneous rock into smaller pieces. This can be caused by:
* Frost Wedging: Water seeps into cracks, freezes, expands, and widens the cracks.
* Abrasion: Rocks are rubbed against each other by wind, water, or glaciers.
* Thermal Expansion/Contraction: Temperature changes cause the rock to expand and contract, weakening it.
* Chemical Weathering: Chemical reactions break down the minerals in the igneous rock. This can be caused by:
* Acid Rain: Acid in rainwater dissolves minerals like calcium carbonate.
* Oxidation: Iron in the rock reacts with oxygen, forming rust (iron oxide).
* Hydrolysis: Water reacts with minerals, breaking them down.
2. Transportation:
* Weathering products (sediments) are carried away by wind, water, or ice to a new location.
3. Deposition:
* Sediments settle and accumulate in layers.
4. Compaction and Cementation:
* The weight of overlying sediment compresses the layers, squeezing out water and air.
* Dissolved minerals precipitate between the sediment particles, acting as a glue (cement) to bind them together. This forms a sedimentary rock.
5. Metamorphism:
* Sedimentary rocks, including those formed from igneous rock fragments, can be buried deep within the Earth's crust.
* The heat and pressure from the surrounding rocks cause the sedimentary rock to recrystallize and change its mineral composition and texture, forming a metamorphic rock.
6. Melting and Crystallization (Back to Igneous):
* If metamorphic rocks or even sedimentary rocks are subjected to even greater heat and pressure, they can melt completely.
* The molten rock (magma) rises to the surface, cools, and crystallizes, forming a new igneous rock. This completes the cycle.
Important Note: The rock cycle is a continuous process. An igneous rock doesn't necessarily have to go through all these stages to become another type of rock. It could be weathered and eroded into sediments, or it could be directly metamorphosed into a metamorphic rock.
