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Physical weathering, also called mechanical weathering or disaggregation, is the class of processes that causes the disintegration of rocks without chemical change. Physical weathering involves the breakdown of rocks into smaller fragments through processes such as expansion and contraction, mainly due to temperature changes.
Many desert features once attributed to wind abrasion, including wind caves, mushroom rocks, and the honeycomb weathering called tafoni, are now attributed to differential weathering, rainwash, deflation rather than abrasion, or other processes. [7] Yardangs are one kind of desert feature that is widely attributed to wind abrasion. These are ...
Chemical weathering processes probably play a more important role in deserts than was previously thought. The necessary moisture may be present in the form of dew or mist. Ground water may be drawn to the surface by evaporation and the formation of salt crystals may dislodge rock particles as sand or disintegrate rocks by exfoliation.
A desert depression is caused by polygenetic factors such as wind erosion, broad shallow warping and block faulting, stream erosion, karst activity, salt weathering mass wasting, and zoogenic processes; representative examples are the large enclosed basins in Africa, such as Farafra, Baharia, Dakhla, Qattara, Siwa and Kargha. [7]
Abrasion is a process of weathering that occurs when material being transported wears away at a surface over time, commonly occurring with ice and glaciers. The primary process of abrasion is physical weathering. Its the process of friction caused by scuffing, scratching, wearing down, marring, and rubbing away of materials.
Along with energy, the water chemistry will also affect the rock exposed to the erosion. Salt, calcium, and acid levels in the ocean have adverse effects on specific rock types. The chemical weathering due to wave processes is part of why wave pounding is so damaging. Wave pounding is not primarily caused by tectonic margins.
Dissolved load is the portion of a stream's total sediment load that is carried in solution, especially ions from chemical weathering. It is a major contributor to the total amount of material removed from a river's drainage basin, along with suspended load and bed load.
Saharan dust (also African dust, yellow dust, yellow sand, yellow wind or Sahara dust storms) is an aeolian mineral dust from the Sahara, the largest hot desert in the world. The desert spans just over 9 million square kilometers, from the Atlantic Ocean to the Red Sea, from the Mediterranean Sea to the Niger River valley and the Sudan region ...