Sandstone is a very common rock. It is made of sand grains cemented together. The grains were once part of a beach or a desert.

Millions of years ago, the sand was buried under other layers of material and waters seeped through the sand as it was slowly squashed by the weight of the material above. This water contained minerals which were deposited between the sand grains (much like lime is deposited on taps), and it stuck (cemented) the grains together. Sometimes the 'cement' was silica, which is difficult to remove. Sandstones made like this are very tough. In other places the cement was more like lime, and this is easier to remove, and such rock is crumbly.

The colour of the sandstone tells you what materials were in the solutions that stuck the sand grains together. If it is orange or red, then the 'cement' contained a lot of iron.

You can often tell desert sandstone because it has wavy lines of different coloured sands in it. Those lines show the top of each sand dune.

Sandstone is often used as a building stone, and buildings made with sandstone include cathedrals and castles. Some older houses are made from sandstone. The word 'brownstone' may even be used for them.

Geologists call sandstone a sedimentary rock. A sediment is something laid down under water or by wind.