The Transformation from Igneous to Sedimentary Rock
1. Weathering and Erosion: Igneous rocks, formed from cooled magma or lava, are exposed at the Earth's surface. Weathering (breakdown of rock) and erosion (removal of weathered material) start to break down the igneous rock into smaller pieces called sediments. This can be caused by:
* Physical weathering: Wind, rain, ice, and temperature changes break the rock into smaller pieces.
* Chemical weathering: Acid rain, oxidation, and other chemical reactions dissolve or alter the rock's minerals.
2. Transportation: These sediments are then transported away from their source by wind, water, or ice. As they travel, they are further broken down and rounded.
3. Deposition: Eventually, the sediments settle in a new location, usually in low-lying areas like lakes, oceans, or riverbeds. Larger sediments tend to settle first, followed by smaller ones.
4. Compaction and Cementation: Over time, the layers of deposited sediments build up, and the weight of the overlying sediments compresses the lower layers. This process is called compaction. Water carrying dissolved minerals seeps through the spaces between sediments. These minerals crystallize and act like glue, binding the sediments together. This process is called cementation.
5. Lithification: The combination of compaction and cementation turns loose sediments into solid rock, forming sedimentary rock.
Examples:
* Granite (igneous) can weather into sand, which can form sandstone (sedimentary)
* Basalt (igneous) can weather into clay, which can form shale (sedimentary)
Important Note: The entire process of transforming igneous rock into sedimentary rock can take millions of years!
