ORIGIN, SEDIMENTARY FEATURES, AND SIGNIFICANCE OF LOW-ANGLE EOLIAN SAND SHEET DEPOSITS, GREAT SAND DUNES NATIONAL MONUMENT AND VICINITY, COLORADO

Low-angle eolian deposits of a sand sheet constitute an areally extensive (710 km2), transitional facies between high-angle eolian dunes and non-eolian deposits. They originate mainly by gentle deceleration of wind, in the lee of small topographic features, which produces a different style of deposition compared to the more extreme flow separation at the brink of a dune slipface. Low to moderate velocities generally remove fine sand from exposed areas, and deposit the sand in nearby topographically lower or sheltered places, resulting in more texturally homogeneous sets of laminae overlying more texturally heterogeneous deposits. Recognition of low-angle eolian deposits may assist in identification of margins of ancient dune fields. -from Authors