Black Sunday

April 14, 1935:

"Black Sunday Storm", the worst dust storm of the U.S. Dust Bowl.
The storm began in the mid afternoon, presaged by thousands of birds fleeing before the rolling clouds of dirt. A long drought during the first half of the 1930s, combined with a lack of knowledge of conservation techniques, caused excessive topsoil erosion on farmlands in the Midwest. Disastrous dust storms like these forced many farmers to leave their homes to start a new life elsewhere, they went to many places especially California. The storm itself was created by a combination of dry topsoil and high (60 mph (97 km/h)) winds.
The Black Sunday storm was the worst dust storm in the Great Plains during the 1930s. It is estimated to have removed 300,000 tons of topsoil from the area known afterwards as the Dust Bowl. The storm of black dust resulted from prolonged drought and overplowing in the Great Plains, which destroyed the sod and left topsoil exposed.

Anybody looking for an interesting history book can pick up Timothy Egan's The Worst Hard Time.