Which type of rock formation involves the compaction and cementation of sediments?

The type of rock formation that involves the compaction and cementation of sediments is sedimentary rock. This process begins with the accumulation of sediments, which can include fragments of other rocks, minerals, and organic materials. Over time, these sediments are buried under additional layers and subjected to pressure.

As pressure increases, the sediments become compacted, reducing the space between them. Meanwhile, mineral-rich water can flow through the spaces in the sediment, allowing minerals to precipitate and bind the particles together, a process known as cementation. This combination of compaction and cementation transforms loose sediments into solid rock, which is characteristic of sedimentary formations.

Other types of rocks, such as metamorphic and igneous, form through different processes. Metamorphic rocks arise from the alteration of existing rocks under pressure and heat, while igneous rocks are formed from the cooling and solidification of molten material. Volcanic rock refers specifically to igneous rock that forms at or near the Earth's surface due to volcanic activity. Therefore, sedimentary rock is the clear choice when discussing the compaction and cementation of sediments.