Erg, reg and hamada
Topic: Landforms and their Evolution: Rivers, Groundwater, Glaciers, Waves and Wind · NCERT: Beyond NCERT
Meaning
Erg, reg and hamada are three types of desert surface:
- Erg: a "sand sea", a wide area covered with dunes.
- Reg: a stony plain covered with gravel and pebbles.
- Hamada: a bare rocky surface, often a plateau. The wind has swept all the sand off it.
They show that most of a desert is not sand. Wind blows the fine grains off some places (hamada and reg) and piles them up in others (erg). All three are found in the Sahara.
Example
The Grand Erg Oriental in Algeria is a huge sand sea in the Sahara. Gravel plains and bare rocky plateaus lie around it.
Don't confuse with
- Desert pavement: this is a thin layer of pebbles that deflation leaves behind on a surface. A reg is a whole gravel plain that covers a large area.
Related concepts
- Aeolian processes
- Deflation
- Wind abrasion
- Sheet flood
- Pediment
- Parallel retreat of slopes
- Pediplain
- Inselberg
- Playa
- Deflation hollow