Which process transforms loose sediments into sedimentary rock?

Which process transforms loose sediments into sedimentary rock?

• A. Metamorphism under high heat and pressure.
• B. Compaction and cementation.
• C. Weathering and erosion.
• D. Melting and crystallization.

Answer: (B)

Compaction and cementation turn loose sediments into sedimentary rock. When sediments are buried, the weight of overlying material squeezes the grains closer together, reducing pore space and bringing them into tighter contact—this is compaction. At the same time, minerals dissolved in water precipitate from groundwater and act like a natural glue, filling the remaining spaces and bonding the grains together through cementation. Together, these two steps lithify the sediment into solid rock, such as sandstone, shale, or limestone, depending on the original material. Metamorphism would require high heat and pressure to alter rock minerals, which isn’t how loose sediments become sedimentary rock. Weathering and erosion break down existing rocks into sediments and move them to new locations, not bind them into rock. Melting and crystallization produce igneous rocks, not sedimentary ones.

Compaction and cementation turn loose sediments into sedimentary rock. When sediments are buried, the weight of overlying material squeezes the grains closer together, reducing pore space and bringing them into tighter contact—this is compaction. At the same time, minerals dissolved in water precipitate from groundwater and act like a natural glue, filling the remaining spaces and bonding the grains together through cementation. Together, these two steps lithify the sediment into solid rock, such as sandstone, shale, or limestone, depending on the original material.

Metamorphism would require high heat and pressure to alter rock minerals, which isn’t how loose sediments become sedimentary rock. Weathering and erosion break down existing rocks into sediments and move them to new locations, not bind them into rock. Melting and crystallization produce igneous rocks, not sedimentary ones.