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No. 93: May-Jun 1994

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The nebraska sand hills: wind or water deposits?

Mosaic of Landsat photographs of northwestern Nebraska
In response to the item in SF#92 about possible massive flooding in Siberia, E. Hansen sent the accompanying mosaic of Landsat photographs of northwestern Nebraska. On this, the famous Nebraska sandhills appear like giant ripples. The width of the mosaic is about 340 kilometers, so you can appreciate the scale of the hills themselves. The crest-to-crest distances seem to be 2-3 kilometers. Roughly 35,000 square kilometers are covered with a sheet of sand that averages 8 meters thick.

Mainstream geologists write these sandhills off as eolian (wind-carried) deposits laid down during the late Pleistocene. Hansen, however, along with geological iconoclast A. Kelly, demur. The Nebraska sanhills, they aver, were actually deposited by a wall of water sweeping down across the continent from the north -- very likely the consequence of an impact of a large asteroid. For more on Kelly's rejection of the eolian theory and many additional examples of deposits by huge tsunamis or marine incursions, see his book Impact Geology and/or category ETM7 in our catalog volume: Carolina Bays, Mima Mounds, etc. (To order the latter book, visit here.)

(Hansen, Evan; personal communication, March 26, 1994.)

From Science Frontiers #93, MAY-JUN 1994. � 1994-2000 William R. Corliss