Sandstone is a sedimentary rock formed by the consolidation of sand grains. Sand is a loose, granular material composed mainly of quartz, with other minerals such as feldspar and mica. When sand is deposited in a river, beach, or other environment where it is subjected to pressure and heat, the grains become cemented together to form sandstone. The cementing material can be silica, calcite, or iron oxide.

Shale

Shale is a fine-grained sedimentary rock formed by the compaction of mud and clay. Mud is a mixture of water, clay minerals, and other fine-grained particles. When mud is deposited in a river, lake, or ocean, it is compressed by the weight of the overlying sediment. This pressure causes the mud to lose its water content and become compacted into shale.

Limestone

Limestone is a sedimentary rock formed by the accumulation and cementation of calcium carbonate (CaCO3). Calcium carbonate is produced by the shells and skeletons of marine organisms, such as corals, mollusks, and foraminifera. When these organisms die, their shells and skeletons sink to the bottom of the ocean and accumulate. Over time, the shells and skeletons are cemented together by calcium carbonate to form limestone.