When pre-existing rocks undergo the process of weathering and erosion, they break down into smaller pieces and eventually form new rocks known as sedimentary rocks. These rocks are the result of the wastage of pre-existing rocks, which can be igneous, metamorphic, or even other sedimentary rocks.

Sedimentary rocks are formed through the accumulation and cementation of sediments, such as sand, silt, and clay, which are carried away by water, wind, or ice. Over time, these sediments are compacted and cemented together to create sedimentary rocks like sandstone, shale, and limestone.

One of the most common types of sedimentary rocks is sandstone, which is composed of sand-sized grains of mineral, rock, or organic material. Sandstone is often used as a building material and can be found in various colors and textures depending on the composition of the original sediments.

Shale is another type of sedimentary rock that forms from the compression of clay and silt particles. It is known for its ability to split into thin layers, making it a popular choice for roofing and flooring materials. Shale is also a valuable source of natural gas and oil, as it can trap these resources within its layers.

Limestone is a sedimentary rock that is primarily composed of calcium carbonate, which is derived from the shells and skeletons of marine organisms. It is often used in construction and as a fertilizer due to its high calcium content. Limestone can also form caves and other karst landscapes through the process of dissolution by acidic groundwater.

Overall, sedimentary rocks are a crucial part of the Earth's geology and provide valuable insights into the history of our planet. By studying the composition and structure of sedimentary rocks, geologists can learn about past environments, climate changes, and even the evolution of life on Earth.

For more information on sedimentary rocks and the processes that form them, visit USGS or Encyclopedia Britannica.

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