1. Weathering and Erosion: This is the breakdown of rocks due to exposure to elements like rain, wind, ice, and temperature changes. This can lead to:
* Physical weathering: Rocks breaking into smaller pieces without changing their chemical composition (like freezing water expanding in cracks).
* Chemical weathering: Rocks changing their chemical composition due to reactions with water, air, or other chemicals (like limestone dissolving in acidic rain).
The broken-down pieces of rock are then transported by wind, water, or ice, leading to erosion.
2. Sedimentation and Lithification: The eroded rock fragments (sediments) are deposited in layers. Over time, these layers are compressed and cemented together, forming sedimentary rocks.
3. Metamorphism: Existing rocks can be transformed by heat and pressure without melting. This can happen deep within the Earth or when rocks are close to magma intrusions. This process creates metamorphic rocks.
So, while melting is a key part of the rock cycle, it's not the only way rocks change form. There are other processes that transform rocks into new types through weathering, erosion, sedimentation, and metamorphism.
