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1.5.1 Loess

Loess is a wind laid deposit of predominantly silt-sized material. Although the origin is somewhat controversial, loess is believed to be of eolian origin. These deposits are generally a few hundred but may be up to several thousand feet thick. Vertical openings caused by decayed roots or grass often characterize loess and impart a vertical permeability higher than the horizontal. The vertical channels or joints often become filled with calcite as precipitation infiltrates and deposits the incrustations. Vertical cuts or faces (artificial or stream caused) are common, and vertical jointing often results in tabular structures up to 40 feet below the top of the cut.


Images
Same loess slope as picture #1 (further along cliff), but 20 years later (1987)
Same loess slope as picture #1 (further along cliff), but 20 years later (1987)
Original from H.H. Einstein
Massachusetts Institute of Technology
Loess in Vicksburg (1967)  Same loess slope as picture #1 (further along cliff), but 20 years later (1987)  Same loess slope as picture #1 (further along cliff), but 20 years later (1987) 

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