What is formed when sediments are compressed and cemented together over time?

Sedimentary rock is formed through a process characterized by the accumulation, compression, and cementation of sediments over time. When particles such as sand, silt, clay, or gravel settle in layers, they eventually become compacted under the weight of additional sediment deposited atop them. This pressure causes the grains to stick together, aided by minerals that precipitate from water in the spaces between the particles, acting as a natural glue.

The formation of sedimentary rock is crucial in various geological processes, as these rocks often preserve fossils and provide information about the Earth's history. They typically form in environments like rivers, lakes, and oceans, where sediment can accumulate over time.

In contrast, igneous rocks are formed from the cooling and solidification of molten material, while metamorphic rocks arise from existing rocks that undergo chemical and physical changes due to heat and pressure, without reaching a molten state. Volcanic rocks are a subset of igneous rocks formed specifically from volcanic activity. Thus, the processes leading to the formation of sedimentary rock differ significantly from those responsible for the formation of the other types of rocks mentioned.