A ghostly face appears to loom out of the soft-orange landscape of the Tirari Desert in South Australia in this image from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite on October 29, 2006. The pale, skeletal-like features are produced by salt deposits in the basin of Lake Eyre, a usually dry salt lake in the lowlands of central South Australia. The lake is Australia’s lowest point, 17 meters (about 56 feet) below sea level.
Ephemeral rivers and streams flow through surrounding deserts into the interior lowland region when it rains heavily, carrying in salty, marine sediments that were laid down in the region in the distant past. The network of streams and creeks is called the Channel Country, but these arteries only fill Lake Eyre on rare occasions. In the 20thcentury, the lake only filled 3 times, most recently in 1989. Since it is usually dry, the lake is a significant source of dust storms in the region, as are dry lakes around the world. The Lake Eyre Basin and surrounding deserts are probably the largest source of airborne dust in the Southern Hemisphere, though the area’s contribution to global dust levels is small compared to locations like the Sahara Desert’s Bodele Depression.