Most eolian deflation zones are composed of _desert pavement_, a sheetlike surface of rock fragments that remains after wind and water have removed the fine particles. Almost half of the Earth’s desert surfaces are stony deflation zones. The rock mantle in desert pavements protects the underlying material from deflation. [Illustration: The sand and rock of China’s Turpan Depression resemble closely those in the view of the Martian surface on page 21.] [Illustration: The arrow points to shiny black desert varnish on these rocks of Egypt’s southwest desert (photograph by Carol Breed).] A dark, shiny stain, called _desert varnish_ or rock varnish, is often found on surfaces of some desert rocks that have been exposed at the surface for a long period of time. Manganese, iron oxides, hydroxides, and clay minerals form most varnishes and provide the shine. Deflation basins, called _blowouts_, are hollows formed by the removal of particles by wind. Blowouts are generally small, but may be up to several kilometers in diameter. Wind-driven grains abrade landforms. Grinding by particles carried in the wind creates grooves or small depressions. _Ventifacts_ are rocks which have been cut, and sometimes polished, by the abrasive action of wind. Sculpted landforms, called _yardangs_, are up to tens of meters high and kilometers long and are forms that have been streamlined by desert winds. The famous sphinx at Giza in Egypt may be a modified yardang. Yardangs of the Lut Desert of Iran. These yardangs are among the largest on Earth, with almost 100 meters of relief. [Illustration: View from Landsat.] [Illustration: View from high-altitude photograph (photograph by U.S. Air Force).] [Illustration: View from low-altitude photograph (photograph by J.T. Daniels).] Eolian transportation Particles are transported by winds through suspension, saltation, and creep. Small particles may be held in the atmosphere in _suspension_. Upward currents of air support the weight of suspended particles and hold them indefinitely in the surrounding air. Typical winds near the Earth’s surface suspend particles less than 0.2 millimeters in diameter and scatter them aloft as dust or haze. _Saltation_ is downwind movement of particles in a series of jumps or skips. Saltation normally lifts sand-size particles no more than one centimeter above the ground, and proceeds at one-half to one-third the speed of the wind. A saltating grain may hit other grains that jump up to continue the saltation. The grain may also hit larger grains that are too heavy to hop, but that slowly _creep_ forward as they are pushed by saltating grains. Surface creep accounts for as much as 25 percent of grain movement in a desert.