Sedimentary rocks form through three main processes: clastic, chemical, and organic.
1. **Clastic Sedimentary Rocks**: These rocks form from the accumulation and compaction of mineral and rock fragments, known as clasts. Over time, these fragments are transported by water, wind, or ice and then deposited in layers. As more layers accumulate, the weight compresses the lower layers, eventually forming solid rock. Examples include sandstone and shale.
2. **Chemical Sedimentary Rocks**: These rocks form when dissolved minerals precipitate from water. This can happen when water evaporates, leaving behind minerals that crystallize and form rocks. Common examples include rock salt and limestone.
3. **Organic Sedimentary Rocks**: These rocks are formed from the accumulation and compaction of organic materials, such as plant debris or animal remains. Over time, these materials are buried and compressed, forming rocks like coal and some types of limestone.
Each of these processes contributes to the diverse types of sedimentary rocks found on Earth.