Search results
Results from the WOW.Com Content Network
The Mississippi River Delta, showing the sediment plumes from the Mississippi and Atchafalaya Rivers, 2001. The modern Mississippi River Delta formed over the last approximately 4,500 years as the Mississippi River deposited sand, clay and silt along its banks and in adjacent basins.
Bangladesh is largely underlain by silt deposits of the Ganges delta. Silt is also abundant in northern China, central Asia, and North America. [5] However, silt is relatively uncommon in the tropical regions of the world. [16] Silt is commonly found in suspension in river water, and it makes up over 0.2% of river sand.
A river delta is so named because the shape of the Nile Delta approximates the triangular uppercase Greek letter delta.The triangular shape of the Nile Delta was known to audiences of classical Athenian drama; the tragedy Prometheus Bound by Aeschylus refers to it as the "triangular Nilotic land", though not as a "delta". [8]
Avulsions are common in river deltas, where sediment deposits as the river enters the ocean and channel gradients are typically very small. [2] This process is also known as delta switching . Deposition from the river results in the formation of an individual deltaic lobe that pushes out into the sea.
The deposits often have distinct layers due to the seasonal and episodic changes in stream flow. [8] Outwash streams often flow into proglacial lakes, where they leave glaciolacustrine deposits. These mainly consist of silt and clay, with laminations on the millimeter scale.
The foreset bed is formed when a stream carrying sediment meets still water. When the stream meets the still water, the velocity of the water is decreased enough so that the larger sediment particles can no longer be carried and are therefore deposited. The deposited sediment builds up over time, and a delta is formed.
A subaqueous fan is a fan-shaped deposit formed beneath water (similar to deltas or terrestrial alluvial fans), that is commonly related to glaciers [1] and crater lakes. [2] Subaqueous fan deposits are generally described as coarse to fine gravel and/or sand, with variable texture and sorting.
In geography and geology, fluvial sediment processes or fluvial sediment transport are associated with rivers and streams and the deposits and landforms created by sediments. It can result in the formation of ripples and dunes , in fractal -shaped patterns of erosion, in complex patterns of natural river systems, and in the development of ...