Which rock type is formed by the compaction and cementation of sediments?

Which rock type is formed by the compaction and cementation of sediments?

• A. Igneous
• B. Metamorphic
• C. Sedimentary
• D. Weathered

Answer: (C)

Sedimentary rocks form when sediments are compacted and cemented together in a process called lithification. As layers of particles accumulate, the weight from above compresses the grains (compaction), and minerals dissolved in water flow between the grains and crystallize, binding the particles into a solid rock (cementation). This is different from igneous rocks, which come from molten rock that cools and solidifies, and from metamorphic rocks, which are transformed by heat and pressure. Weathered describes the breakdown of rocks into smaller pieces and isn’t a rock type itself.

Sedimentary rocks form when sediments are compacted and cemented together in a process called lithification. As layers of particles accumulate, the weight from above compresses the grains (compaction), and minerals dissolved in water flow between the grains and crystallize, binding the particles into a solid rock (cementation). This is different from igneous rocks, which come from molten rock that cools and solidifies, and from metamorphic rocks, which are transformed by heat and pressure. Weathered describes the breakdown of rocks into smaller pieces and isn’t a rock type itself.