With respect to size, the most common sedimentary deposits in the ocean are mud and sand, with gravel a distant third; boulder and tiny particles (colloids) are extremely rare in the sea (Pinet 1992).

However, beaches may be composed of sediments of various sizes: (from finest to coarsest) mud (silt and clay), sand, and gravel (cobbles and boulders). Scientists generally use Wentworth’s grain-size distribution chart for sediment size analysis. Typically, people associate beaches with quartz sand, but remember, sand is a grain size (1/16 mm to 2 mm), not a rock type. Beach sediments are found in all shapes and sizes and may be composed of any rock type (i.e., igneous, metamorphic, or sedimentary).