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Landscapes – a journey across Saudi Arabia

Flying across Saudi Arabia, particularly from north to south, you might be forgiven for thinking it is totally sand, interspersed with bright rings of green vegetation dotted at random accross the landscape.

Indeed, just over one third of the country (700,000 square kilometrs) is covered by desert. The Rub’ Al Khali, also known as ‘The Empty Quarter’ is the largest sand desert in the world. In the north of the country the Great Nefud desert covers 60,000 square kilometers. Between these lies the Dahna, a vast arc of dunes that runs over 1,000 kilometres and joins the two great sand seas. The bright green rings are circles of wheat. Using huge watering pipes that irrigate circles for growing crops, Saudi is now a major producer of wheat.

While the view from the air gives an impression of featureless land, on the ground the reality is very different. The sands themselves are of many different types. Where did they come from? Essentially, they are formed from the granite and coarse-grained igneous rocks of the Arabian Shield. As the granite was eroded, its component parts crumbled into quartz and feldspar and individual crystals broke free as coarse sand. As time passed, the softer feldspar broke down even further into dust while the quartz grains, being much harder, took much longer to have their angular shape softened by further erosion.

Sand dunes

Dunes come in many shapes and sizes but there are four basic configurations:

Transverse
These occur when the wind blows predominantly from the same direction. The ridges run perpendicular to the wind’s direction. They are long, gently rounded ridges often with a steep face on the lee side. Crescent dunes also form in these conditions with the convex side to windward. Crescent dunes are mobile and will spread the desert into surrounding areas.

 

Longitudinal
These are long, rolling dunes. They tend to be quite stable and often have grass and bushes growing on them particularly in the hollows. They are the typical dunes of the Nefud.

 

Sand Mountains
As their name implies, these are huge mounds of sand rising to over 300 metres. Some of the biggest are in the south east corner of the Rub al Khali.

 

 

Uruq
In Arabic Uruq means veins or roots and this describes their shape, long and thin with well defined edges and a sharp ridge on top.

 

The sands are being constantly blown by the wind, forming dunes of differing shapes and sizes. Whilst generally the desert is barren, the occasional shower of rain produces a transformation. Plants and flowers appear with amazing rapidity. They have to grow quickly as the rain is unlikely to reoccur for some considerable time. They therefore have to sprout, flower and drop their seeds back onto the sand in double quick time. The seeds will then lie dormant until the next rains. In the Dahna arc of dunes, rain regularly falls in spring and the dunes are covered with grasses. These are prized for the grazing they provide for herds of goat, sheep and camels.

In the Great Nefud desert rain falls very seldom and the landscape is bleak. Even more so is the Rub al-Khali where, between huge dunes, there are great areas of gleaming white sabkha; the result of rivers and lakes that dried up many centuries ago.

An amazing journey

Saudi Arabia contains many differing landscapes. If you were to undertake a journey across the country from east to west, a journey of 1,400 kilometres, what would you see?

Sabkhaf and salt marshes

Assuming you don’t want to use the excellent highways, you will need a four-wheel drive vehicle – remembering that less than 100 years ago all journeys would have had to be made by camel! Leaving the low-lying shoreline of the Arabian Gulf, you would encounter sabkhas, salt marshes where the underlying water is being constantly lost through evaporation, thus leaving the salt behind. The water comes from rain, underground aquifers and near the coast, seawater. With evaporation, the surface is a hard salt crust, which is comparatively smooth, but just below the surface there is a salty mush. Drive carefully across the sabkha, as any vehicle or animal breaking the surface crust finds itself in deep trouble and many have been lost in this way.

Did you know?The sabkha continues inland for up to 100 kilometres from the coast and even by then the land has risen to no more than 50 metres above sea level. Although inhospitable, a surprising number of plants live there. You would almost certainly see the desert hyacinth – not as pretty as the hyacinth in your own garden, but very similar in shape. Eventually, you will reach a low, east-facing cliff with isolated steep jebels (hills) surrounding the al Ahsa oasis. You are now onto the Summan plateau. The action of the waves on the shore back in the Pliocene era deeply undercut the soft rock leaving, in the Jebel Qara oasis, caves cut into the heart of the jebel. This is a favourite spot for tourists.

Summan Plain

The land now stretches as a featureless plain for 300 kilometres to the northwest with little to see on the surface. However, just below, in the soft, crumbling soil, marine fossils, molluscs and sharks’ teeth are plentiful. Further along, the surface changes to duricrust, a thin skin of hard, cemented limestone covering soft, porous stone. The ground here is riddled with tunnels and caves, the only visible sign of which are the small holes known as dahls, which give access to the subterranean landscape. The Summan Plain’s bleak aspect is relieved at this point by occasional rawdat (the plural of ‘riyadh’, meaning ‘garden’ or ‘meadow’).

Reaching the city of As Salamiyah, you turn slightly south westerly and head towards Jeddah. Leaving the Rub al Khali to your left, you encounter much hillier country with increasingly dramatic rocky outcrops, divided by deep wadis .Wadis are old riverbeds where pools of water may remain, the result of the infrequent rainfall. Sometimes, the pools may be fed from underground aquifers. Here, as elsewhere in the desert, wherever water, the essential element of survival is present, you can be sure to find humans and animals.

Westwards to the coast

As you continue your journey westwards, you will encounter spectacular mountains, 2-3000 metres high, where the rock takes on fantastic shapes, carved by the wind and rain. The land rises slowly, through Rumah to Riyadh and on to Makkah, with the highest most spectacular escarpment to be found at Jebel Tuwaiq. One hundred kilometres west of the Tuwaiq escarpment you will have reached the start of the Arabian Shield – dark, forbidding hills followed by desolate countryside, a black basalt plain stretching into the distance.. Strange shapes have been formed by the molten rock, which has the appearance of frozen black treacle, interspersed with wadis and tunnels. This was a land of volcanoes – an immense volcanic explosion scattering rocks for miles around formed the crater at Wahbah. Extinct volcanoes dot the landscape, and if you can struggle up one of these, you will be rewarded with spectacular views and see the skin of white salt that sits at the crater bottom.

Approaching the coast, you come to some of the most picturesque country in Saudi Arabia; fine mountain views with the Tihama Plain in the distance. As the road plunges down through Wadi ad Dila and crosses the Tihama River, at last we see the Red Sea with its coral reefs and reach the end of our journey.


mOre For more information:

Origins of Arabia
Andrew Thompson, ISBN 1-900-988-046

Websites:
www.nederworldphotos.com/saudiarabia2.html
www.ashfordplatt.com/1-landscapes.htm


Photographs courtesy of Peter Sanders and John Smith.


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