Deposits of Sand: Ripples Versus Dunes - Dune Worlds: How Windblown Sand Shapes Planetary Landscapes - page 59

Fig. 5.11 Compositional sorting. Eureka dunes, north of Death
Valley National Park, showing concentrations of dense dark grains
of magnetite. Thin lamellae of magnetite are exposed as rather pretty
curves and loops in the slip face of the dune at left, with some patches
of magnetite in the background. At right, differential concentration of

magnetite grains on the sides of aeolian ripples on the dunes shows
them much more starkly. Upper right inset: while jabbing eyeglasses
into sand dunes is not generally a good idea, these ones have small
magnets, which show clearly the magnetic nature of the dark grains.
Photo by R. Lorenz

Fig. 5.12 Vertical view of
typical aerodynamic ripples,
coral pink sand dunes, State Park,
Utah. Ripple wavelength is
*15 cm. Notice that while the
pattern is quite regular, there are
some defects forming Y-
junctions (see Chap. 19 ) . Photo J.
Zimbelman