| • Science | • People | • Locations | • Timeline |
The valley averages approximately 1 mi (1.6 km) wide, with the valley floor averaging between 300-600 ft (90-180 m) below the surrounding bluffs. The valley was extensively dammed between 1946 and 1966 to provide a series of reservoirs in the Dakotas. Geologically, the valley separates the main plateau of the Great Plains to the west from the Coteau du Missouri to the east.
Although cultivation has added markedly to the sediment in the river as it flows through the valley, the water was turbid even before the widespread introduction of agriculture, according to early European travellers. Erosion and deposition are believed to be in equilibriumFor the 2002 science fiction movie see Equilibrium (2002 movie Equilibrium or balance is any of a number of related phenomena in the natural and social sciences. In general, a system is said to be in a state of equilibrium if all influences on the system in the trench. SiltSilt refers to soil or rock particles of a certain very small size range (see grain size). On the Wentworth scale, silt particles fall between 0. 063 mm (4 62. 5 μm), larger than clay but smaller than a sand. In actuality, silt is chemically distinct fation now provides a major challenge for the impounded sections of the river in the valley.