Landscapes Shaped by Wind and Water Processes
- Landforms created by the removal of material through wind or water action.
- Landforms formed by the accumulation of sediment transported by wind or water.
- Elevated flat-topped landforms shaped by erosion.
Erosional Features
Rock Pedestals: Sculpted by Wind
- Imagine a tall, narrow rock formation standing alone in the desert, its base eroded into a slender column while the top remains wide and intact.
- This is a rock pedestal, a striking example of wind erosion.
Rock pedestals are sometimes called mushroom rocks due to their unique shape.
How Are Rock Pedestals Formed?
- Abrasion: Wind carries sand particles that act like sandpaper, eroding the base of the rock more than the top.
- Differential Erosion: Softer rock layers erode faster than harder ones, creating the pedestal shape.
- Undercutting: The base becomes narrower as erosion continues, while the top remains relatively intact.
The White Desert in Egypt showcases rock pedestals shaped by wind-driven sand over thousands of years.
Wind erosion is most effective near the ground, where sand particles are heaviest and most concentrated.
Wadis: Dry Riverbeds Carved by Water
Wadis
Dry riverbeds found in arid regions, formed by the powerful erosive force of seasonal floods.
How Do Wadis Form?
- Flash Floods: Intense, short-lived rainstorms create torrents of water that carve deep channels into the landscape.
- Erosion: The rushing water erodes the riverbed, widening and deepening it over time.
- Drying: Once the floodwaters recede, the riverbed remains dry until the next flood.
Wadi Rum in Jordan is a famous example, with its deep, winding channels surrounded by towering cliffs.
Wadis are often used as travel routes in deserts due to their flat terrain, but they can be dangerous during flash floods.
Depositional Features
Dunes: Formed by Wind
Dunes
Mounds of sand shaped by wind patterns, varying in size and shape depending on wind direction, sand supply, and vegetation.
Types of Dunes
Barchan Dunes:
- Crescent-shaped with horns pointing downwind.
- Formed in areas with a single dominant wind direction and limited sand supply.
The Sahara Desert is home to many barchan dunes.
