Dry areas created by global circulation patterns contain most of the
deserts on the Earth. The deserts of our world are not restricted by
latitude, longitude, or elevation. They occur from areas close to the
poles down to areas near the Equator. The People’s Republic of China has
both the highest desert, the Qaidam Depression that is 2,600 meters
above sea level, and one of the lowest deserts, the Turpan Depression
that is 150 meters below sea level.
Deserts are not confined to Earth. The atmospheric circulation patterns
of other terrestrial planets with gaseous envelopes also depend on the
rotation of those planets, the tilts of their axes, their distances from
the Sun, and the composition and density of their atmospheres. Except
for the poles, the entire surface of Mars is a desert. Venus also may
support deserts.
[Illustration: The Garlock fault, near the bottom of this Landsat image,
is generally considered to be the geologic border between the Mojave
Desert in the south and the Great Basin Desert in the north. The Great
Basin contains more than 150 discrete desert basins separated by more
than 160 mountain ranges.]