Other Dunes and Other Sand Deposits - Dune Worlds: How Windblown Sand Shapes Planetary Landscapes - page 90

Fig. 7.3 A view downwind
from the small Superstition
Mountains in Southern
California, where linear dunes
several hundred meters long have
formed in the lee of the
mountains. When these were
documented by Greeley et al.
(1978), they trailed into chains of
barchans (as at Mars in Fig. 7.7 ),
but the sand mobility may have
been reduced since the 1970s
when that study was made. The
site is presently used as an area
for off-road driving (see Chap. 22
). The proliferation of vehicle
tracks on these dunes may influ-
ence the morphology by rounding
slip faces and influencing the
sand mobility. Photo R. Lorenz

Fig. 7.4 Moenkopi plateau in
Northern Arizona, from a
commercial airliner looking East.
Note that the dunes tail from
headlands rather than the gullies
up which the sand presumably
moves. Photo R. Lorenz

surrounding the base of the plants. In some instances (e.g.,
Fig. 7.9 ) the attenuation of the airflow by the plant allows a
lee dune to form. Nebka (another Arabic term; they can also
be called 'coppice dunes') can be misinterpreted to be dome
dunes with plants on top of them. On other planets, large
blocks or other obstacles might take the place of the
stabilizing vegetation, sheltering sand and indurated fines
from wind erosion.

7.8 Parabolic Dune

A 'U'-shaped feature with two horns that are typically much
longer than the thick arcuate deposit that connects the horns
on the downwind side of the feature (Fig. 7.10 ). The horns
of the 'U' are stabilized by vegetation, although possibly
rocks or large blocks might serve as the stabilizing role on
other planetary surfaces, and only a single slip face is