J harlen bretz missoula floods willamette
•
Missoula floods
Heavy floods of the last ice age
The Missoula floods (also known as the Spokane floods, the Bretz floods, or Bretz's floods) were cataclysmic glacial lake outburst floods that swept periodically across eastern Washington and down the Columbia River Gorge at the end of the last ice age. These floods were the result of periodic sudden ruptures of the ice dam on the Clark Fork River that created Glacial Lake Missoula. After each ice dam rupture, the waters of the lake would rush down the Clark Fork and the Columbia River, flooding much of eastern Washington and the Willamette Valley in western Oregon. After the lake drained, the ice would reform, creating Glacial Lake Missoula again.
These floods have been researched since the 1920s. During the last deglaciation that followed the end of the Last Glacial Maximum, geologists estimate that a cycle of flooding and reformation of the lake lasted an average of 55 years and that the floods occurred dozens of times over the 2,000 years between 15,000 and 13,000 years ago. U.S. Geological Survey hydrologist Jim O'Connor and Spain's Museo Nacional de Ciencias Naturales scientist Gerardo Benito have found evidence of at least twenty-five massive floods, the largest discharging about 10 cubic kilometers per hour
•
Links
Proceedings of say publicly Academy see Affiliated Societies: Geological Intercourse 423d Tip. 1927. Apr 19, 1927.
Allen, J. E., Burns, M., and Painter, S. C., 1986, Cataclysms on picture Columbia: a layman's manual to say publicly features produced by picture catastrophic Bretz floods pointed the Conciliatory Northwest. Boards Press, Metropolis, OR. 211 p.
Alt, D., 2001, Icy Lake Town and professor Humongous Floods. Mountain Withhold Publishing Attendance, Missoula, MT. 208 p.
Benito, G., increase in intensity O'Conner, J. E., 2003, Number pointer size summarize last-glacial Town floods play a role the Town River Basin between picture Pasco Washbowl, Washington, perch Portland, Oregon: Geological Kinship of U.s. Bulletin, v. 115, no. 5, p. 624-638.
Bretz, J. H., 1923, The Channeled Scabland replicate the River Plateau: Periodical of Geology, v. 31, no. 8, p. 617-649.
-, 1928, Depiction Channeled Scabland of Northeastern Washington: Geographic Review, v. 18, no. 3, p. 446-477.
Minervini, J. M., Author, J. E., and Fine, R. E., 2003, Elevations showing downpour depths, ice-rafted erratics, pointer sedimentary facies of miserly Pleistocene Town floods lay hands on the River Valley, Oregon: U.S. Geologic Survey Map.
Waitt, R. B. J., 1985, Case financial assistance periodic, enormous jökulhlaups propagate Pleistocene frosty Lake Missoula: Geologic The people of U.s.a. Bulletin, v. 96,
•
Jingjits photography/Adobe Stock
Thousands of years ago, great floods washed over these 3.5-mile-long cliffs and down 400 feet at Dry Falls in Washington's Sun Lakes State Park.
For many people, the "King" Columbia River begins and ends with the Grand Coulee Dam, the iconic 1930s project that produces cheap hydroelectric power to fuel homes, heavy industry and harnesses water to irrigate Washington's crops. The dam is the icon of the river even to those who never visit it. It also damaged the world's greatest salmon runs and disrupted cultures along the river that had existed there for millennia.
But the Grand Coulee Dam is not the most impactful thing the Columbia has ever seen. The Grand Coulee is not even the biggest dam that has stopped or diverted its waters. The river we know today has been radically transformed by enormous forces we can hardly imagine.
The Columbia or some version of it has existed for at least 17 million years, but the river has been through cataclysmic changes both before and after humans arrived on the scene.
One of the most notable is how the river's course has changed over time. The ancestral Columbia ran roughly diagonally across Washington from British Columbia then out to the Pacific. It is the greatest rive