Bar (river morphology)

Point bar at a river meander: the Cirque de la Madeleine in the Gorges de l'Ardèche, France.

Gravel bar in the American River, Washington, United States.

A bar in a river is an elevated region of sediment (such as sand or gravel) that has been deposited by the flow. Types of bars include mid-channel bars (also called braid bars, and common in braided rivers), point bars (common in meandering rivers), and mouth bars (common in river deltas). Bars are typically found in the slowest moving, shallowest parts of rivers and streams,^[1] and are often parallel to the shore and occupy the area farthest from the thalweg.^[2]

The locations of bars are determined by the geometry of the river and the flow through it. Point bars form on the inside of meander bends in meandering rivers because the shallow flow and low shear stresses there reduce the amount of material that can be carried there. The excess material falls out of transport and forms the bar.

See also

• Pendant bar (geology)
• River island

References

Wikimedia Commons has media related to gravel bar.

Further reading

• John Bridge and Robert Demicco (2008). Earth Surface Processes, Landforms and Sediment Deposits. Cambridge, UK: Cambridge University Press. ISBN 978-0-521-85780-2. 

Wikisource has the text of the 1911 Encyclopædia Britannica article Bar (ridge of sand).