Comment: 19:20 - 20:45 (01:25)
Source: Annenberg/CPB Resources - Earth Revealed - 15. Weathering and Soils
Keywords: "Richard Hazlett", "soil erosion", tropic, "rain forest", "Midwestern United States", "dust bowl", draught, wind, soil, weathering, dust, grassland, agriculture, glacial, plant, crop, topsoil, farming
Our transcription: Soil erosion is not limited to tropical rain forests.
It is, in fact, a worldwide problem that can take many different forms.
In the 1930's, the American Midwest experienced a catastrophe of major proportions--the dust bowl.
Draught conditions combined with high winds to blow the region's soil into massive swirling clouds of dust.
The famous dust bowl of the American Midwest occurred between 1934 and 1938, and the natural circumstances that led to that catastrophe really were not unusual.
High seasonal winds are common in the Midwest and draught occurs cyclicly -- it's a common part of that environment.
What was unusual was the fact that the grassland there had been removed by agriculture, by grazing, and the loose soil underneath, a lot of which is dust, blown in from past glacial events, was free and exposed to the wind -- so away it blew.
And this was a catastrophe that didn't slow down, that continued because of a sustained draught.
Plowed fields were stripped bare of top soil, planted crops were ruined, buried in piles of dust.
For many farmers the result was bankruptcy.
Geology School Keywords