Gravel, small stones found in natural deposits or beds. The stones normally range in size from 14 inch (6 mm) to 2 12 inches (6 cm) in diameter, although the range sometimes is much larger. They are usually rounded and without irregular edges, differing in this respect from crushed rock. (Another difference is that gravel occurs naturally, while crushed rock is made by breaking up large stones.)
Gravel results from the action of glaciers, flowing water, waves, and the weathering of larger pieces of rock. Beaches and riverbeds are often good sources of gravel. Commercial gravel is sorted into various sizes through wire screens. The most important use of gravel is in making concrete. It is also used as paving material, as a base for paving material, and as railroad ballast.