Why do deserts have sand

Calcium carbonate precipitated from solution may cement sand and gravel into hard layers called "calcrete" that form layers up to 50 meters thick. Caliche is a reddish-brown to white layer found in many desert soils. Caliche commonly occurs as nodules or as coatings on mineral grains formed by the complicated interaction between water and carbon dioxide released by plant roots or by decaying organic material. Plants Sparse, very dry, single-species vegetation in Death Valley, California.

Most desert plants are drought- or salt-tolerant. Some store water in their leaves, roots, and stems. Other desert plants have long tap roots that penetrate the water table, anchor the soil, and control erosion.

The stems and leaves of some plants lower the surface velocity of sand-carrying winds and protect the ground from erosion. Deserts typically have a plant cover that is sparse but enormously diverse.

The giant saguaro cacti provide nests for desert birds and serve as "trees" of the desert. Saguaro grow slowly but may live years. When 9 years old, they are about 15 centimeters high.

After about 75 years, the cacti are tall and develop their first branches. There are many different shapes of dunes. When it rains in the desert a lot of water falls all at once. Hard, dry ground does not soak up water very easily. Most of the water flows on top of the ground causing floods. Sand, silt and even rocks are washed away.

Temporary rivers and streams form to carry away the water and sediment. Many deserts contain large salt flats. Minerals like sodium chloride table salt are dissolved in rain or ground water. Water quickly evaporates in the dry desert air and the salt is left behind. Ancient deserts that have turned into sedimentary rocks are shown in mint green with horizontal lines on the bedrock geology map of the United States of America.

Static map. The Sahara's vast, harsh landscape is home to little life, but hardy animals and vegetation can be found in sparse pockets like the Merzouga oasis in Morocco. Friday, April 19, These are the words typically used to describe the desert. But the endless, wind-swept dunes that come to mind only make up a small percentage of the deserts on the planet.

A desert is actually just a place that has very little precipitation. Subtropical deserts like the Sahara are what people generally imagine when they think about the desert. The Sahara has rocky plateaus as well as sand dunes. Despite these temperatures, the Sahara is home to olive trees, antelope , jerboa , scorpions, jackals, and hyenas.

The largest desert on Earth is Antarctica, which covers The ice that covers the area is on average 2. There is almost no vegetation in Antarctica, so the animals that live there are mostly carnivores, such as penguins, albatrosses, whales, and seals. How can both the Sahara and Antarctica be deserts? The reason is that they both see little precipitation during the course of a year, typically around 25 centimeters 10 inches , or less.

Many successful solar power plants have been built in the Mojave Desert. These plants have a combined capacity of megawatts MW making them the largest solar power installation in the world. The potential for generating solar energy from the Sahara desert is immense. European interest in the Sahara Desert stems from its two aspects: the almost continual daytime sunshine and plenty of unused land.

The Sahara receives more sunshine per acre than any part of Europe. The Sahara Desert also has the empty space totalling hundreds of square miles required to house fields of mirrors for solar plants.

The Negev Desert, Israel, and the surrounding area, including the Arava Valley, receive plenty of sunshine and are generally not arable.

This has resulted in the construction of many solar plants. Both world wars saw fighting in the desert. The Turks were defeated by the British, who had the backing of irregular Arab forces that were seeking to revolt against the Turks in the Hejaz, made famous in T. Warfare in the desert offered great scope for tacticians to use the large open spaces without the distractions of casualties among civilian populations. Tanks and armoured vehicles were able to travel large distances unimpeded and land mines were laid in large numbers.

However the size and harshness of the terrain meant that all supplies needed to be brought in from great distances. The victors in a battle would advance and their supply chain would necessarily become longer, while the defeated army could retreat, regroup and resupply.

For these reasons, the front line moved back and forth through hundreds of kilometers as each side lost and regained momentum. Marco Polo arriving in a desert land with camels. The desert is generally thought of as a barren and empty landscape. It has been portrayed by writers, film-makers, philosophers, artists and critics as a place of extremes, a metaphor for anything from death, war or religion to the primitive past or the desolate future.

There is an extensive literature on the subject of deserts. View of the Martian desert seen by the probe Spirit in Mars is the only planet in the Solar System on which deserts have been identified. The Martian deserts principally consist of dunes in the form of half-moons in flat areas near the permanent polar ice caps in the north of the planet.

The smaller dune fields occupy the bottom of many of the craters situated in the Martian polar regions. Skip to main content. Search for:.

Cold desert: snow surface at Dome C Station, Antarctica. Exfoliation of weathering rocks in Texas. One square centimeter 0. Dust storm about to engulf a military camp in Iraq, Aerial view of Makhtesh Ramon, an erosion cirque of a type unique to the Negev. Diagram showing barchan dune formation, with the wind blowing from the left. Windswept desert pavement of small, smooth, closely packed stones in the Mojave desert.

Flash flood in the Gobi. Tadpole shrimp survive dry periods as eggs, which rapidly hatch and develop after rain. Shepherd near Marrakech leading his flock to new pasture. Salt caravan travelling between Agadez and the Bilma salt mines.

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