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A confluence is the point at which two streams flowing from different directions unite. This photo shows a confluence of two streams, approximately equal in size and width, draining the basement complex in north-central Nigeria.
Rwanda is known as the country of a thousand hills. These hills are mostly made of Precambrian rocks. However, the valleys between these hills are filled with alluvial deposits that provide a fertile soil for cultivation. Photo taken in the Kigali district.
In sedimentology, a channel is a lensoidal architectural element with a concave erosional base.
As meandering rivers move on a floodplain they can generate distinctive cross-stratified deposits related to lateral migration of point bars. The cross-set at the center of the photo is several meters thick.
After a flooding event, when waters are carrying much suspended sediment, the bed of a river can suffer siltation, becoming extensively covered by relatively fine-grained particles. This picture shows an example of this process from southern Nigeria.
WATER: Stream meanders, Horseshoe Park, Rocky Mountain National Park --- Water descending rapidly down a canyon forms a straight path, but when it arrives in an almost level valley it meanders as shown in this picture. The lower Mississippi River shows similar meanders.