Deserts: Landforms+Life

Desert Landforms:

Deserts have diverse and unique landforms that are shaped by wind and water erosion, deposition, and weathering. Some of the common desert landforms are:

- Dunes: mounds or ridges of sand that are formed by wind blowing over loose sand. Dunes can have different shapes and sizes depending on the wind direction, speed, and sand supply. Some examples of dune types are barchan, transverse, longitudinal, star, and parabolic dunes.

- Salt flats: large areas of land formed by the evaporation of ancient lakes. They are composed of crystallized salt, minerals, and clay, creating a smooth and reflective surface that stretches for miles.

- Playas: flat areas of clay or salt that are formed by the evaporation of water from temporary lakes or ponds. Playas can be dry or wet depending on the season and rainfall. They often have cracks or polygons on their surface due to contraction and expansion.

- Alluvial fans: cone-shaped deposits of sediment that are formed by streams flowing from mountains to plains. Alluvial fans can be active or inactive depending on the water availability and erosion rate. They often have braided channels or deltas on their surface.

- Mesas and buttes: flat-topped hills or mountains that are formed by erosion of horizontal layers of rock. Mesas are larger than buttes, which are larger than pinnacles or chimneys. They often have steep cliffs or escarpments on their sides.

- Arches and bridges: natural openings or spans in rock that are formed by erosion of softer layers or joints. Arches have no support below them, while bridges have support on both sides. They often have delicate or spectacular shapes.

- Desert varnish: is a thin coating of minerals and organic matter that forms on exposed rocks in arid regions. It is composed mainly of iron and manganese oxides, clay minerals, and sand grains. Desert varnish can have different colors, from red to black, depending on the chemical composition and environmental conditions. Desert varnish is a result of chemical and biological processes that occur over thousands of years on the rock surface.

- Desert Pavement: area is covered by a layer of closely packed rocks. Desert pavement is formed by a process called deflation, in which the finer particles of sand and dust are blown away, leaving behind the coarser and heavier rocks.

Desert Life:

Deserts are home to a variety of plants and animals that are specialized to survive in harsh conditions. Some of the specialization include:

- Drought tolerance: plants and animals can reduce water loss or store water in their tissues or organs. For example, cacti have thick stems with spines instead of leaves, camels have humps with fat reserves, and kangaroo rats have efficient kidneys that produce concentrated urine.

- Heat tolerance: plants and animals can regulate their body temperature or avoid heat stress by behavioral or physiological means. For example, succulents have waxy coatings or hairs that reflect sunlight, reptiles have scales or shells that insulate them from heat, and rodents have burrows or nocturnal habits that keep them cool.

- Food scarcity: plants and animals can obtain nutrients from limited or specialized sources or store food for future use. For example, acacia trees have symbiotic relationships with ants that protect them from herbivores, insects have mouthparts or digestive enzymes that allow them to feed on sap or nectar, and foxes have caches or dens where they store food.

Deserts are also rich in cultural diversity and human history. Many civilizations have thrived in deserts by developing irrigation systems, trade networks, art forms, religions, and technologies. Some examples of desert cultures are the Egyptians, the Bedouins, the Berbers, the Tuare.

Conclusion:

Deserts are arid regions that receive very little precipitation. They cover about one-fifth of the Earth's land surface and can be found on every continent.  There are 23 deserts in the world. Deserts have extreme temperatures, ranging from scorching hot to freezing cold.

Points to Ponder:

Are deserts of not much value or do they have vital importance for the planetary ecosystem?



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