Which type of rock is formed from sediments accumulating and compacting over time?

Sedimentary rocks are formed through a process where sediments—composed of minerals, organic matter, and particles—accumulate in layers over time. As these layers build up, they undergo compaction due to the weight of additional layers pressing down on them. This compaction, along with the cementation process, solidifies the sediments into rock.

Sedimentary rocks often contain fossils, indicating they formed in environments where organisms lived, which further emphasizes their relationship with sediment accumulation. Understanding the formation of sedimentary rocks is vital in geology, as they can provide significant insights into Earth’s history, including past climates, processes, and the evolution of life.

The other types of rocks mentioned do not form in the same manner: metamorphic rocks are formed from existing rocks subjected to high pressure and temperature, igneous rocks result from the cooling and solidification of molten material, and "fossil rocks" is not a recognized category in geology, although fossils can be present in sedimentary rocks.