crossstratified

Cross-stratification is a geological term used to describe a type of sedimentary structure where layers of sediment are deposited at an angle to the main body of sediment. This occurs when the direction of sediment transport changes, often due to changes in flow velocity or direction. Cross-stratification is commonly observed in environments such as river channels, deltas, and beaches, where sediment is transported by flowing water or wind.

The layers that form cross-stratification are known as cross-beds or cross-strata. These beds typically exhibit a characteristic inclination, with the angle of inclination varying depending on the energy of the transporting medium. In rivers, for example, cross-beds may form at angles of 10-30 degrees, while in wind-blown sand, the angles can be much steeper.

Cross-stratification is an important indicator of past depositional environments and can provide valuable information about the conditions under which sediment was deposited. It is often used in conjunction with other sedimentary structures to interpret the ancient depositional setting and to reconstruct past environments.

Cross-stratification can be preserved in the rock record and is often visible in outcrops and in thin sections of sedimentary rocks. The study of cross-stratification is a key component of sedimentology, the branch of geology that focuses on the study of sediments and sedimentary rocks.