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  1. 1. DESERTS
  2. 2. What is a desert? What do deserts look like? What makes a desert? Where are deserts found?
  3. 3.  Deserts can be found all over the world.
  4. 4.  Deserts are the most brutal areas here on Earth.  Their most fundamental characteristic is a shortage of available moisture for plants, resulting from an imbalance between precipitation and evaporation. Which means they can frequently lose more moisture through evaporation than they receive from annual precipitation.  Dry soil becomes sensitive to erosion processes which carries sand and shapes rocks, creating a beautiful but unwelcoming landscapes.
  5. 5. Types of deserts
  6. 6. Sahara of Northern Africa, Kalhari of Southern Africa, and the Great Australian Desert. Subtropical deserts
  7. 7. Gobi, Takla Makan Continental deserts
  8. 8. Deserts east of the Sierra Nevada Mountains, California & Nevada, East of the Cascades of Oregon and Washington, and East of the Andes Mountains in South America. Cold winter deserts
  9. 9. Atacama Desert of coastal Peru, Namib Desert of coastal South Africa. Coastal deserts
  10. 10. Northern Greenland, and ice- free areas of Antarctica. Polar deserts
  11. 11. Desert surfaces Sand covers only about 20% of desert surfaces, most of it in vast sand sheets and sand seas.
  12. 12. Desert surfaces Hamadas are relatively level plains that are covered by boulders and exposed bedrock.
  13. 13. Aeolian processes Erosion is the process by which soil and rock are removed from the Earth's surface by exogenic processes such as wind or water flow, and then transported and deposited in other locations.
  14. 14. Aeolian processes Wadi is the Arabic term that refers to a valley. In some cases it can also refer to a dry riverbed that only experiences water when there is a heavy rain fall.
  15. 15. Aeolian processes A mushroom rock, also called a pedestal rock, is a naturally occurring rock whose shape, as its name implies, strikingly resembles a mushroom.
  16. 16. Aeolian processes A yardang is a streamlined hill carved from bedrock by the dual action of wind abrasion, and deflation.
  17. 17. Aeolian processes Tafoni are small cave- like features found in granular rock such as sandstone, with rounded entrances and smooth concave walls, often connected.
  18. 18. Dunes  Wind plays an important role in deserts. It moves large amounts of soil around, covering much of the world's deserts with sand. About half of the sand fields of hot deserts exist as sand dunes.  A dune is a hill of sand built by either wind or water flow.  The shapes and sizes of dunes change constantly, but they can be grouped into a few simple categories: linear, star, and barkhan dunes.
  19. 19. Linear (longitudinal) dunes Dunes
  20. 20. Star dunes Dunes
  21. 21. Crescent sand dunes, also called barkhan or transverse Dunes
  22. 22. At first glance, it may seem as there is not much in a desert. The land may seem empty. The quiet suggests that there are few or no animals. The weather may not seem friendly to life. But if we look closer, a desert is made of ecosystems. In an ecosystem, plants, animals, land, water and air work together. Deserts can be filled with life!
  23. 23. Thank you for attention! Igor Nemanjić