Pedregous deserts: What are they, how they form and examples

Pedregous deserts are vast arid extensions characterized by being mainly covered with stones, gravels and rocksinstead of sand. Unlike sandy deserts, which are associated with large mobile dunes, stony deserts have a firm and rocky surface that can be extended by kilometers. These areas are found in different regions of the world and represent a significant part of the desert areas of the planet.

Throughout the world, stony deserts receive different names depending on the region. In North Africa, particularly in Sahara, they are known as “REGG”. This term refers to a plain covered by compacted stones and pebbles, which has been exposed after the wind took the finest sand particles. On the other hand, in mountainous areas or desert plateaus, it is common to hear the term “Hamada”which describes hard rock surfaces, often formed by wind erosion and temperature fluctuations. In Australia, these deserts are called “Gibbers”referring to the plains covered with shot songs, which have been polished by the wind and time.

At first glance, stony deserts may seem hostile and inert terrain, but they have unique characteristics that differentiate them from other types of deserts:

• Rocking and stable surface: Unlike sand deserts, stony plains offer a firmer soil that facilitates vehicle traffic compared to mobile dunes.
• Extreme temperatures: Pedregous deserts experience extreme temperature variations, with very hot days and extremely cold nights.
• Low vegetation: Plant life is scarce due to the lack of water and the soil that is not fertile. Only some plants adapted to drought, such as bushes or cacti, manage to survive in these environments.
• Visible erosion: It is common to observe rock formations eroded by the action of wind and sand, creating landscapes with curious and unique forms.

You may also be interested in knowing the biotic and abiotic factors of the desert.

The formation of stony deserts is a geological and climatic process that occurs throughout thousands or even millions of years. Next, the main stages of this phenomenon are detailed:

1. Erosion of rocks: Fragmentation by natural agents

The first step in the formation of stony deserts is weathering or mechanical or physical weathering, which fragments larger rocks in smaller particles without altering their chemical composition. This process is caused by:

• Extreme temperature fluctuations: During the day, the intense heat causes the rocks to expand, and at night, the cold causes its contraction. Over time, this repeated expansion and contraction generates cracks that end up decomposing the rocks.
• Wind and water action: Although the deserts are arid, the occasional rains and the strong winds contribute to the wear of the rocks, accelerating their fragmentation. Here you can read about water erosion: definition, types, causes and consequences.

2. Elimination of fine particles: deflation and wind erosion

In arid regions, the wind is a key agent in wind erosion. This process, known as deflation, consists in the elimination of lighter sediments, such as sand and dust, which are transported by air currents. As a result, only the most weighing materials remain on the surface, such as gravels and stones.

In this other post you can learn more about wind erosion: definition, types and examples.

3. Compaction and stabilization of the soil

With the passage of time, the process of eliminating the finest sediments gives way to a layer of rocks and pebbles that protects the underlying ground from greater erosion. This rock mantle acts as a natural barrier against the action of the wind, stabilizing the landscape and preventing the surface from being easily dragged.

4. Formation of a hard and resistant surface

As the stones are exposed, they can form a compact crust on the ground. Sometimes, the minerals on the ground and occasional precipitation help consolidate this layer, producing a more stable and erosion resistant surface. This structure is characteristic of stony deserts, also called as regg, Hamada or Gibbers.

This set of processes (weathering, wind erosion, defaction, compaction and consolidation of the land) is what gives rise to the stony landscapes of the world’s deserts.

Let’s see what some of the most important stony deserts in the world are:

• Sahara Desert (Africa): The Sahara desert is the largest warm desert in the world, with an extension of approximately 9.2 million km². Although it is usually associated with sand dunes, in reality more than 70 % of its surface is stony. In this link you can meet the animals of the Sahara desert.
• Gibson Desert (Australia): It covers approximately 156,000 km² and is largely composed of a type of stony desert known locally as gibbers. These surfaces are covered by a dense layer of rolled songs that have been smoothed due to wind erosion.
• Gobi desert (Mongolia and China): The Gobi desert, which extends for approximately 1.3 million km², is another prominent example of stony desert. Although it has some areas of dunes, most of the Gobi is composed of gravel and rock plains, which makes it a cold desert due to its extremely icy winters.
• Atacama Desert (Chile): The Atacama desert, located in northern Chile, is one of the most arid places on the planet, with rainfall less than 1 mm annual in some areas. Although it has some dunes, a large part of its surface is naked rock and gravel. In these other posts you can discover more information about why it does not rain in the Atacama desert and Flora and Fauna of the Atacama desert.
• Hamada du Draa (Morocco and Algeria): The Hamada Du Draa is an extensive rock plateau located in the Western Sahara, on the border between Morocco and Algeria. It is a classic example of Hamada, where eroded rocks and shot songs predominate.
• Karakum desert (Turkmenistan): The Karakum desert occupies around 70 % of the territory of Turkmenistan and covers more than 350,000 km². Although it has some dunes, most of it is a stony desert with gravel areas and compacted floors.

If you want to read more articles similar to Pedregous deserts: What are they, how they form and exampleswe recommend that you enter our category of ecosystems.