Which type of rock is formed from ancient sand deposits?

Sandstones are formed from ancient sand deposits that have been cemented together over time. These deposits typically consist of grains of sand, which are primarily composed of quartz or feldspar, although they can also include other minerals. The process of lithification, which involves compaction and cementation of the sand particles, leads to the formation of sandstone. This type of rock often displays features like layering and grain size variations, reflecting its sedimentary origins.

In contrast, granites are igneous rocks formed from the solidification of molten magma, while limestones originate primarily from the accumulation of organic materials such as shells and coral, or from chemical precipitation. Shales are also sedimentary rocks, but they are derived from the compaction of silt and clay materials rather than sand. Understanding the specific processes and materials that lead to the formation of different rock types is crucial in geology and helps identify past environmental conditions.