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                                                4

RIVERS

STS086.ESC.0008115 Coppename River, Suriname River, Suriname
STS086.ESC.00081321 Amazon River, Brazil
STS076.ESC.07022920 Senegal (meandering river, abandoned arm, almost oxbow lakes)

Meanders

STS076.ESC.01080736 Amazon River, Brazil
STS076.ESC.07191919 Pakistan
STS076.ESC.06232512 Nile River

On many floodplains, channels follow curves and bends called meanders.  The channels cut through unconsolidated sediment and easily eroded bedrock.  Meanders can migrate over periods of years, eroding the outside of beds where the current is strongest.  Curved sandbars, called point bars, are deposited on the inside banks, where the current is slower.  As the bends grow closer and closer together the river may bypass a loop and take a new shorter course, leaving behind an oxbow lake.

[[image]]
(a) Erosion at outside bend
Deposition of point bar at inside bend
[[image]] 
Position of strongest current shifts from side to side
[[image]]
(c) Silt and clay deposits in former channel connections
Oxbow lake
[[image]]
Direction of meander migration
A Sedimentation
Maximum velocity
B Erosion

From Press and Siever, 1998, Understanding Earth, Second Edition.