Hamada

Hamada

Discussion
Ask a question about 'Hamada'
Start a new discussion about 'Hamada'
Answer questions from other users
Full Discussion Forum
 
Encyclopedia

A hamada is a type of desert
Desert
A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...

 landscape consisting of largely barren, hard, rocky plateaus, with very little sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...

. A hamada may sometimes also be called a reg , though this more properly refers to a stony plain rather than a highland.

Hamadas exist in contrast to ergs
Erg (landform)
An erg is a broad, flat area of desert covered with wind-swept sand with little or no vegetative cover. The term takes its name from the Arabic word ʿarq , meaning "dune field"...

, which are large areas of shifting sand dunes.

The world's largest hamada is the Hamada du Draa
Draa River
The Draa is Morocco's longest river . It is formed by the confluence of the Dadès River and Imini River. It flows from the High Atlas mountains south-ward to Tagounit and from Tagounit mostly westwards to the Atlantic Ocean somewhat north of Tan-Tan...

, in the northwest Sahara
Sahara
The Sahara is the world's second largest desert, after Antarctica. At over , it covers most of Northern Africa, making it almost as large as Europe or the United States. The Sahara stretches from the Red Sea, including parts of the Mediterranean coasts, to the outskirts of the Atlantic Ocean...

 desert, between Morocco
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...

, Algeria
Algeria
Algeria , officially the People's Democratic Republic of Algeria , also formally referred to as the Democratic and Popular Republic of Algeria, is a country in the Maghreb region of Northwest Africa with Algiers as its capital.In terms of land area, it is the largest country in Africa and the Arab...

 and Moroccan Sahara. Hamada areas form 70% of the Sahara desert.

Formation


Hamadas are produced by the wind removing the fine products of weathering: a process known as deflation. The finer products are removed in suspension, whilst the sand is removed through saltation
Saltation (geology)
In geology, saltation is a specific type of particle transport by fluids such as wind or water. It occurs when loose material is removed from a bed and carried by the fluid, before being transported back to the surface...

 and surface creep, leaving behind a landscape of gravel
Gravel
Gravel is composed of unconsolidated rock fragments that have a general particle size range and include size classes from granule- to boulder-sized fragments. Gravel can be sub-categorized into granule and cobble...

, boulder
Boulder
In geology, a boulder is a rock with grain size of usually no less than 256 mm diameter. While a boulder may be small enough to move or roll manually, others are extremely massive....

s and bare rock.