Introduction - Dune Worlds: How Windblown Sand Shapes Planetary Landscapes - page 10

Fig. 1.15 Living in the Antarctic is perhaps a close analogy to how
people might one day live on other planets. Quartz is not the only
material on Earth to be blown by wind and form dunes—snow can do
so as well, especially when very cold and dry. As the old dome at the
South Pole became buried by blowing snow, the new Amundsen-Scott

South Pole Station was built 1999-2008 on stilts to allow snow to
blow under it, and the building was somewhat aerodynamically-
shaped, with the wedge-shaped underside oriented into the prevailing
wind specifically to inhibit snow accumulation. Photo National

Science Foundation

Whether active today, or fossils of the past, dunes tell us
certain things about the conditions of their formation. There
must be sand—whatever it happens to be made of, it means
particles of a size with the right mobility. In some cases, this
means particles that have been ground down from massive
rock, sometimes evaporite crystals formed as a lake dries up,
sometimes it means sand re-liberated from sandstone rock
that was once in the form of dunes. Yet in other cases (as at
Titan) it may mean grains built up from smaller particles
somehow, or falling from the sky as with snow on Earth.
Like the dunes it can form, sand itself evolves—often ini-
tially jagged or sharp-cornered from its origin in fracture or
precipitation, the innumerable collisions with its fellows as it
bounces along the ground may grind it smaller or make it
round. New analytical methods, and even remote sensing,
can let us match the minerals from which a grain or dune is
made to a locale where the grain must have come from.
Other laboratory techniques can even tell us how long a sand

grain has been buried inside a dune, letting us gauge the
dune's age. Yet the microscopic properties of sand grains
can influence such experiential phenomena as how the sand
sounds when jump on a dune and make the sand slide.
In addition to telling us about past climates, sand and
dunes are a major factor in how humans live and work in
some desert environments. Large deserts have been barriers
to commerce and military operations and many different
machines and/or techniques have been developed to enable
vehicular travel across sand dunes. Some of the first tra-
verses of the Sahara were made with half-track vehicles,
also a favourite 1 of World War II's 'Desert Fox', Erwin
Rommel (Fig. 1.13 ).

1 During the preparation of this topic, we searched for images in the
Bundesarchiv but sadly failed to find any of this vehicle on an actual
dune. Most operations were (prudently) on the flat coastal plains and in
the mountains.