Sandstone
Explanation
Rocks are classified into three major groups based on their mode of formation: Igneous, Sedimentary, and Metamorphic. The process described in the question refers to lithification, which is the consolidation of loose sediments into solid rock through compaction and cementation.
Option Analysis:
- Basalt: Incorrect. Basalt is an extrusive igneous rock formed by the rapid cooling and solidification of lava on the Earth's surface. It is not formed from sediments.
- Granite: Incorrect. Granite is an intrusive igneous rock formed by the slow cooling and crystallization of magma beneath the Earth's surface.
- Sandstone: Correct. Sandstone is a sedimentary rock composed mainly of sand-sized mineral particles or rock fragments. It is formed when layers of sand accumulate and are subjected to pressure (compression) and the precipitation of minerals (hardening/cementation) over geological time.
- Slate: Incorrect. Slate is a metamorphic rock derived from shale (a sedimentary rock) that has undergone low-grade metamorphism due to heat and pressure. It is not formed directly from loose sediments but from the alteration of existing rock.
Key Takeaway:
Sedimentary rocks (e.g., Sandstone, Limestone, Shale) are the only rock type formed by the lithification (compaction and cementation) of loose sediments derived from the weathering and erosion of pre-existing rocks.