What geological process forms sedimentary rock?

Sedimentary rock forms through a process known as lithification, which involves the compaction and cementation of sediments over time. As sediments accumulate, they are subjected to pressure from the weight of overlying materials. This pressure compresses the sediments and causes them to lithify, resulting in the formation of sedimentary rock.

In the context of this process, lithification not only includes the physical compaction of sediments but also the chemical processes that bind these particles together, often involving minerals that precipitate from water and fill the spaces between sediment grains. This understanding of lithification highlights why sedimentary rock is distinct from other types of rock, such as igneous or metamorphic, which form under different conditions.

The other geological processes described—such as cooling of magma, heat and compression from tectonic shifts, and melting and reshaping of existing rocks—are associated with the formation of igneous and metamorphic rocks, which arise from entirely different mechanisms involving thermal activity or significant structural change in existing rock formations.