Here's why:

* Formation: Red sandstones are formed from the accumulation and cementation of sand-sized grains, which are primarily composed of quartz and feldspar.

* Color: The red color comes from iron oxides, specifically hematite, which are deposited within the sandstone during its formation.

* Sedimentary Process: The sand grains are transported by wind or water, eventually settling and being buried under layers of sediment. Over time, these layers are compacted and cemented together, forming sandstone.

Additional details:

* Types of Red Sandstones: There are different types of red sandstones, including:

* Arkose: Contains a significant amount of feldspar, giving it a slightly pinkish hue.

* Quartz arenite: Primarily composed of quartz grains, resulting in a more vibrant red color.

* Greywacke: Contains a mixture of quartz, feldspar, and rock fragments, often with a darker red coloration.

Let me know if you have any other questions!