Which rock type forms from the accumulation and lithification of sediments?

Which rock type forms from the accumulation and lithification of sediments?

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

Answer: (B)

Sedimentary rocks form when sediments accumulate, become buried, and undergo lithification, which means they are compacted and cemented into solid rock. The sediments originate from the breakdown of preexisting rocks through weathering and erosion and are transported by wind, water, or ice, then deposited in layers in environments like rivers, lakes, or oceans. Over time, the weight of overlying layers compresses the lower sediments (compaction), and minerals dissolved in water act as glue to cement the grains together (cementation). This combination turns loose sediments into rock. Examples include sandstone from sand grains, shale from clay, and limestone from carbonate sediments. In contrast, igneous rocks form from the cooling and solidification of molten material, and metamorphic rocks form when existing rocks are altered by heat and pressure without melting. Extrusive refers specifically to igneous rocks that crystallize on the surface after eruption or rapid cooling.

Sedimentary rocks form when sediments accumulate, become buried, and undergo lithification, which means they are compacted and cemented into solid rock. The sediments originate from the breakdown of preexisting rocks through weathering and erosion and are transported by wind, water, or ice, then deposited in layers in environments like rivers, lakes, or oceans. Over time, the weight of overlying layers compresses the lower sediments (compaction), and minerals dissolved in water act as glue to cement the grains together (cementation). This combination turns loose sediments into rock. Examples include sandstone from sand grains, shale from clay, and limestone from carbonate sediments. In contrast, igneous rocks form from the cooling and solidification of molten material, and metamorphic rocks form when existing rocks are altered by heat and pressure without melting. Extrusive refers specifically to igneous rocks that crystallize on the surface after eruption or rapid cooling.