Graded bedding

Graded bedding is a sedimentary layer whose particles change progressively in size, commonly becoming finer upward as a sediment-laden flow loses energy.

Normal grading: A sedimentary bed that becomes finer upward from its base. This common pattern forms as a waning flow deposits coarse grains before fine ones.
Sediment transport: The movement of sediment by water, wind, ice, or gravity. Grading develops as transported particles are sorted and deposited.
Turbidite: A sediment deposit formed by a turbidity current, commonly in deep-water settings. Many turbidites contain graded layers that record the waning current.
Cross-bedding: Inclined layers within sedimentary beds formed as ripples or dunes migrate. It records migrating bedforms rather than progressive grain-size change through a bed.
Inverse grading: A sedimentary bed that becomes coarser upward. It reverses the usual upward-fining pattern and can form in granular flows.
Sedimentation: The settling or accumulation of particles from a fluid or at Earth's surface. Graded bedding is a pattern produced during sediment accumulation.
Flysch: A thick succession of deep-water sedimentary rocks, commonly containing repeated turbidites. Repeated graded beds help identify the turbiditic origin of flysch successions.
Graded bedding (igneous): A vertical variation in crystal size or composition within an igneous rock layer. The phrase also describes igneous layering, but this page concerns sedimentary deposits.
Turbidity current: A sediment-laden current that flows downslope underwater because it is denser than surrounding water. Its waning deposits commonly produce upward-fining graded beds.
Grain size: A measure of the diameter of sediment particles, commonly expressed with the Wentworth scale. A progressive change in grain size defines graded bedding.

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