The Missouri River Trench is the geological name applied to the broad valley of the Missouri River as it flows southward through North Dakota and South Dakota in the United States.
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 equilibrium in the trench. Siltation now provides a major challenge for the impounded sections of the river in the valley.
Famous quotes containing the words missouri river, missouri, river and/or trench:
“Then they seen it, the old Missouri River shinin’ in the moon and across it the lights of St. Louis.”
—Dudley Nichols (1895–1960)
“I was losing interest in politics, when the repeal of the Missouri Compromise aroused me again. What I have done since then is pretty well known.”
—Abraham Lincoln (1809–1865)
“Hard by the lilied Nile I saw
A duskish river dragon stretched along.
The brown habergeon of his limbs enamelled
With sanguine alamandines and rainy pearl:
And on his back there lay a young one sleeping,
No bigger than a mouse;”
—Thomas Lovell Beddoes (1803–1849)
“Grammar is the logic of speech, even as logic is the grammar of reason.”
—Richard Chenevix Trench (1807–1886)