Last Updated on December 20, 2022
Rocky deserts, also called hamada, consist of vast expanses of rocks that the wind has stripped of all debris produced by meteoric degradation; pebbly deserts, called serir or reg, derive from ancient alluvial deposits from which the wind has removed the finer debris component.
The desert landscape can take on different aspects depending on the prevailing erosion and deposition processes.
The name “hamada” (or “hammada”) comes from Arabic and means “rock”, and it is used to describe a desert region that is dominated by rocky terrain and a lack of soil.
The hamada has higher temperature ranges than any other desert types, while common to all is the rapidity of the soil in changing from cold to hot as the sun appears and disappears.
Because of this, rocky deserts mostly experience extremely hot temperatures during the day which drop to near-freezing at night.
Vegetation, except for the presence of oasis-generating surface water, consists mainly of shrubs, brushwood and thistles. The hamada is more suitable for the passage of mechanical means of transportation rather than that of animals.
The nature of the hamada leads it to be the least humid of the deserts, making it the most hostile to human life. The soil structure is permeable and water is quickly absorbed.
The most common rocks in the hamada are limestone, sandstone, basalt and crystalline rocks (such as granite and gneiss).
Overall, the hamada is formed by a combination of geological and climatic processes that shape the landscape over time, working together to create a harsh and unforgiving environment that is characterized by rocky terrain and a lack of vegetation
Hamadas are produced by means of deflation, a phenomenon which occurs when the wind lifts and moves sand and all loose material from the surface, leaving only the larger rock formations. It takes place by three mechanisms: traction/surface creep, saltation, and suspension.
The finer-grained products are taken away in suspension, while the sand is removed through saltation and surface creep, leaving behind a landscape of gravel, boulders and bare rock.
Some of the processes that contribute to the formation of the hamada include:
- Erosion: The rocky terrain of the hamada is formed by erosion, which is the process by which wind and water wear away at the surface of the earth. Over time, the wind and water can erode the rocks and soil of the hamada, leaving behind a landscape dominated by rocky outcrops and cliffs.
- Deposition: In some cases, the wind and water of the hamada can also deposit sediment, such as sand and gravel, in the desert landscape. This can lead to the formation of features like sand dunes and alluvial fans.
- Climate: The dry climate of the hamada is another factor that contributes to its formation. The lack of rainfall and high temperatures of the desert environment can make it difficult for plants to survive, leading to a barren, rocky landscape.
Rocky Deserts of the World
Rocky deserts can be found in many parts of the world, including Africa, the Middle East, and North and South America.
One of the most important examples of hamada is the Tinrhert rocky plateau in Algeria. The largest hamada is found in the western Sahara desert. It is the most widespread form of desert in the Sahara; in fact, it occupies about 70 percent of its area.
Other rocky deserts are present in the middle east, such as the Negev desert in Israel or parts of the Arabian desert in Qatar, as well as certain areas of the Lut desert in Iran, which is also one of the smallest and the hottest desert in the world.
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