1. Weathering:
* Physical Weathering: This breaks down rocks into smaller pieces without changing their chemical composition. Examples include freezing/thawing, abrasion, and plant roots.
* Chemical Weathering: This alters the chemical makeup of rocks, causing them to break down. Examples include oxidation (rusting), acid rain, and dissolving by water.
2. Erosion:
* Once rocks are broken down, they are transported by wind, water, or ice to new locations. This process is called erosion.
3. Deposition:
* As the energy of the transporting agent decreases, sediments settle out in layers. This process is called deposition. Rivers, lakes, oceans, and deserts are common depositional environments.
4. Compaction:
* Over time, the weight of overlying sediments compresses the lower layers, squeezing out water and air. This process is called compaction.
5. Cementation:
* Dissolved minerals in groundwater precipitate between the sediment grains, acting like glue to bind them together. This process is called cementation.
Types of Sedimentary Rocks:
* Clastic sedimentary rocks: Formed from fragments of other rocks. Examples: sandstone, shale, conglomerate.
* Chemical sedimentary rocks: Formed by precipitation of minerals from solution. Examples: limestone, rock salt, gypsum.
* Organic sedimentary rocks: Formed from the remains of living organisms. Examples: coal, oil shale.
Key Points:
* Sedimentary rocks are the only rocks that can contain fossils.
* They provide clues about Earth's past environments and climates.
* They are an important source of resources like oil, natural gas, and groundwater.
