Sandstone is a type of rock made from tiny grains of sand that have been pressed together and cemented over millions of years. If you've ever built a sandcastle and watched it crumble, you've seen loose sand. Sandstone is what happens when sand gets buried deep underground, squeezed by the weight of other rocks above it, and glued together by natural minerals dissolved in water seeping through the layers.

You can often see the individual sand grains in sandstone if you look closely, and it usually feels rough or gritty to the touch. The rock comes in many colors: red, brown, yellow, white, or gray, depending on what minerals are mixed in with the sand. The famous red rocks of the American Southwest are mostly sandstone, their striking color coming from iron oxide (basically rust) coating the sand grains.

Sandstone is surprisingly useful. Because it's relatively soft compared to rocks like granite, people can cut and shape it easily for building. Many historic buildings, from ancient temples to Victorian townhouses, were constructed from sandstone. The rock also holds oil and water underground, making it important for wells and energy production.

Geologists love sandstone because it often contains fossils and tells stories about ancient deserts, beaches, and rivers where the original sand piled up long before dinosaurs existed.