Reversing Dunes
Wind Direction: During much of the year wind
blows from the southwest toward the Sangre de Cristo Mountains in
the northeast.
Angle of Repose: When the angle of repose is exceeded by the dune, a sand
avalanche occurs on the lee side of the dune. The illustration above represents
a cross-section of the classic barchan dune type.
Wind Reversal: It is common for winds to come from
the opposite direction. This greatly alters the dune morphology (hold
your cursor over the lower image above). One reason the Great Sand Dunes
reach such great heights is due to reversing winds. Reversing dunes grow
atop themselves rather than moving forward across the landscape. A surface
feature created on the crests of reversing dunes is a Chinese
wall.
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