bedded

Bedded is an adjective used in geology to describe rocks or sediments that display bedding, a primary layering produced by the orderly deposition of material over time. A bed is a discrete layer, and a bedding plane separates consecutive beds. The term is most often applied to sedimentary rocks.

Bedding planes reflect changes in sediment supply, grain size, composition, or depositional environment. They are typically parallel and near-horizontal in the original outcrop, but can be tilted, rolled, or folded by later tectonic forces. Within beds, additional structures such as cross-bedding or ripple marks may record current directions and flow conditions, while finer laminations indicate quieter deposition. Bedding is a primary (formation) feature, in contrast to metamorphic foliation, which develops under high pressure and temperature.

Common bedded rocks include sandstone, shale, limestone, and siltstone. These rocks form in a variety of environments, such as rivers, deltas, lakes, and shallow marine settings. The character of each bed—its thickness, color, mineral content, and texture—often changes from layer to layer, providing a record of past environmental conditions.

Significance in geology and related fields lies in the ability of bedding to organize sediments into a stratigraphic sequence. Bedded rocks enable correlation between distant outcrops, reconstruction of paleoenvironments, and interpretation of sedimentary history. In resource geology, bedded formations can influence porosity and permeability, affecting groundwater flow and hydrocarbon reservoirs.