What is the method of rock formation that involves sediment fragments building up over time due to pressure?

• A. Metamorphism
• B. Extrusion
• C. Cooling of magma
• D. Compaction and cementation

Answer: (D)

The method of rock formation involving sediment fragments accumulating and solidifying over time due to pressure is known as compaction and cementation.

During this process, sediments such as sand, silt, and clay are deposited in layers over time. As additional layers accumulate, the weight of the upper layers exerts pressure on the lower layers, causing the sediments to compact together. This compaction reduces the volume of the sediment layers, increasing their density.

Simultaneously, minerals present in water can fill the spaces between the compacted sediment particles. This process of cementation binds the particles together, transforming loose sediments into solid sedimentary rock. This combination of pressure and mineral binding is essential in forming rocks like sandstone, shale, and limestone, which are all classified as sedimentary rocks.

Understanding compaction and cementation is crucial in the study of geology, especially when examining the formation of sedimentary layers in various environments over geological timescales.