Waterworn

Waterworn describes rocks, minerals, and sediments that have been shaped and smoothed by prolonged exposure to moving water. It is a form of mechanical weathering produced by abrasion, collision, and polishing as particles are transported by rivers, streams, or ocean currents. The term is often used in geology, sedimentology, and archaeology to distinguish materials whose surfaces and shapes reflect watery transport rather than wind or ice.

During transport, rough edges are knocked off and surfaces become smooth and rounded. The degree of rounding and polish depends on transport distance, water velocity, the sediment load, and the hardness of the particles. Over time, waterworn grains may become well-rounded pebbles or even sand grains with a smooth surface. In coastal environments, wave action can produce polished, elongated, and striated surfaces on shell and rock fragments; in rivers, one commonly finds waterworn gravels composed of rounded quartz, chert, or other durable minerals.

Waterworn textures can be distinguished from wind-worn or ice-worn by their characteristic smoothing patterns and the setting of deposition. While waterworn grains are ubiquitous in river and beach deposits, recognition of their transport history can aid in interpreting sediment provenance, paleoenvironment, and archaeological contexts where artifacts or shells show marine or fluvial wear.