Point bar

A point bar is a deposit of sediment that builds along the inside bank of a river meander, where slower flow encourages deposition.

Helicoidal flow: A spiral-shaped flow in a river channel that carries water and sediment across and around the channel. This secondary circulation moves sediment from the outer bank toward the inside bend.
Alluvium: Unconsolidated sediment deposited by flowing water. Point bars are alluvial deposits formed within active river channels.
Fluvial geomorphology: The study of landforms shaped by rivers and the processes that create them. Point bars are evidence used to explain how river channels shape landscapes.
Mississippi River: A major North American river flowing from Minnesota to the Gulf of Mexico. Its meandering reaches and deposits provide classic examples of point-bar development.
Meander: A winding bend in a river channel that migrates across a floodplain. Point bars form on the inside of these bends as their channels migrate.
Grain size: A measure of the dimensions of individual sediment particles. Changes in grain size help distinguish bar deposits and their depositional conditions.
Stratigraphic architecture: The three-dimensional arrangement and relationships of sedimentary rock bodies. Ancient point-bar deposits form recognizable packages within fluvial strata.
Oxbow lake: A crescent-shaped lake formed when a river cuts off a meander bend. Cutoff can isolate a former bend beside the point-bar deposits it built.
Lateral accretion: The sideways growth of a sediment body as successive deposits accumulate along its edge. Point-bar surfaces grow outward through successive layers of lateral deposition.
Sedimentary structure: A feature in sediment or sedimentary rock produced during or shortly after deposition. Point-bar deposits preserve structures that record changing flow and sediment transport.

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