The Dust Bowl was a period of severe dust storms that greatly damaged the ecology and agriculture of the American and Canadian prairies during the 1930s. The phenomenon was caused by a combination of natural factors (severe drought) and human-made factors: a failure to apply dryland farming methods to prevent wind erosion, most notably the destruction of the natural topsoil by settlers in the region. The drought came in three waves: 1934, 1936, and 1939–1940, but some regions of the High Plains experienced drought conditions for as long as eight years.

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关键人物Theodoric the GreatAlfred the GreatOtto I the GreatAbbas the Great