Figure 18.15

Ergs. (A) This astronaut photograph shows a small portion of the Rub’ al Khali erg (or the Empty Quarter) in Oman. The sand dunes shown here, mainly longitudinal dunes, are about 100 m (330 ft) high (inset photo). Salt flats (or sabkhas) have formed between the dunes. (B) The Sahara has the greatest concentration of ergs of any region. The largest ones are mapped here.

(A. © Felix Bleichenbacher; inset, NASA image created by Robert Simmon, using Landsat data provided by the United States Geological Survey)