Several formations create a desert's geological landscape.
Desert landscapes geologically vary the world over, despite sharing some inherent traits. To be considered a desert area, the land must receive less than 10 inches of total yearly rainfall; by that definition, deserts in the southwestern United States and northern Africa are similar to Antarctica. But many people consider the picture of sand, rocks and sparse animal and plant life to be trademarks of deserts, some of the world's most inhospitable landscapes on the planet. Does this Spark an idea?
Dunes
Sand dunes are billowy hills created by high winds in deserts like the sections of the Mojave and Sonoma of southern California and parts of Arizona. The tall deposits of sand particles are much more prevalent in the vast wastelands of northern and central Africa's Sahara and Asia's Gobi, where the dunes are can reach more than 1,000 feet in height. Geologists categorize dunes by five shapes. All dunes, however, have essentially two sides: the leeward, which faces away from the wind, and the windward, which faces the wind.
Mesas and Fans
Mesas and buttes jut well above the flat landscapes of American deserts. These features are characterized by flattened tops leveled by desert wind and help form the canyon walls of many American deserts. Another geological feature prevalent in many deserts are alluvial fans, sand and sediment deposits that collect into fan-shaped formations as a result of runoff from sudden flash floods. Similar to fans are arroyos, deep depressions in the desert floor that also result as water channels its way to the lowest points of a landscape.
Other Features
Several other erosive formations make up the geological landscape that form from both high winds and flash flooding. Blowouts are deeply depressed areas in the desert floor that result from the near constant battering of high winds. Blowouts can be recognized by the fact that plant life such as cacti species that have anchored themselves into the soil will be perched atop small columns. Enough blowouts and erosion can cause hoodoos, which are tall, rocky columnlike formations that form in the interiors of canyons.
The Desert Floor
Flash floods and wind are responsible for moving sand and rock to create desert geological structures. The displaced sand and sediment often finds it's way to the desert floor, where it hardens into what geologists call "desert pavement." Rocks, sand and grit too heavy to be carried far by the wind settle into small cracks and crevices, where they harden into this "pavement." Sometimes a chemical reaction occurs among the minerals, producing a reflective sheen known as a desert's "varnish."
Tags: high winds, American deserts, create desert, create desert geological, desert floor
