Rub' al Khali
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|Rub' al Khal (الربع الخالي)|
Sand dunes in the Rub' al Khali.
|Countries||Saudi Arabia, Oman, United Arab Emirates, Yemen|
|Length||1,000 km (621 mi)|
|Width||500 km (311 mi)|
|Area||650,000 km2 (250,966 sq mi)|
The Rub' al Khali (Arabic: الربع الخالي ar-Rubʿ al-Ḫālī ,[note 1] "the empty quarter") or Empty Quarter is the largest sand desert in the world, encompassing most of the southern third of the Arabian Peninsula. The desert covers some 650,000 square kilometres (250,000 sq mi) (the area between long. 44°30′ −56°30′E., and lat. 16°30′ −23°00′N) including parts of Saudi Arabia, Oman, the United Arab Emirates, and Yemen. It is part of the larger Arabian Desert.
The desert is 1,000 kilometres (620 mi) long, and 500 kilometres (310 mi) wide. Its surface elevation varies from 800 metres (2,600 ft) in the southwest to around sea level in the northeast. The terrain is covered with sand dunes with heights up to 250 metres (820 ft), interspersed with gravel and gypsum plains. The sand is a reddish-orange color due to the presence of feldspar.
Along the middle length of the desert there are a number of raised, hardened areas of calcium carbonate, gypsum, marl, or clay that were once the site of shallow lakes. These lakes existed during periods from 6,000 to 5,000 years ago and 3,000 to 2,000 years ago. The lakes are thought to have formed as a result of "cataclysmic rainfall" similar to present-day monsoon rains and most probably lasted for only a few years. However, lakes in the Mundafen area in the southwest of the Rub' al Khali show evidence of lasting longer, up to 800 years, due to increased runoff from the Tuwaiq Escarpment.
Evidence suggests that the lakes were home to a variety of flora and fauna. Fossil remains indicate the presence of several animal species, such as hippopotamus, water buffalo, and long-horned cattle. The lakes also contained small snails, ostracods, and when conditions were suitable, freshwater clams. Deposits of calcium carbonate and opal phytoliths indicate the presence of plants and algae. There is also evidence of human activity dating from 3,000 to 2,000 years ago, including chipped flint tools, but no actual human remains have been found.
The region has a hot desert climate typical of the larger Arabian Desert. The region is classified as "hyper-arid", with typical annual rainfall of less than 30 millimetres (1.2 in). Daily maximum temperatures average at 47 °C (117 °F) and can reach as high as 51 °C (124 °F).
Fauna includes arachnids (e.g. scorpions) and rodents, while plants live throughout the Empty Quarter. As an ecoregion, the Rub' al Khali falls within the Arabian Desert and East Saharo-Arabian xeric shrublands.
Geologically, the Empty Quarter is the most oil-rich site in the world. Vast oil reserves have been discovered underneath the sand dunes. Sheyba, at the northeastern edge of the Rub' al Khali, is a major light crude oil-producing site in Saudi Arabia. Ghawar, the largest oil field in the world, extends southward into the northernmost parts of the Empty Quarter.
Desertification has increased through the millennia. Before desertification made the caravan trails leading across the Rub' al Khali so difficult, the caravans of the frankincense trade crossed now virtually impassable stretches of wasteland, until about AD 300. It has been suggested that Ubar or Iram, a lost city, depended on such trade. The traces of camel tracks, unidentifable on the ground, appear in satellite images. More recently, tribal populations were also present in certain parts of the Empty Quarter, with the largest in the Najran region. A few road links were connected with these tribal settlements to the water resource and oil production centers.
The first documented journeys by non-resident explorers were made by British explorers Bertram Thomas in 1931 and St. John Philby in 1932. Between 1946 and 1950 Wilfred Thesiger crossed the area several times and mapped large parts of the Empty Quarter including the mountains of Oman.
In June 1950, a US Air Force expedition crossed the Rub' al Khali from Dhahran, Saudi Arabia, to central Yemen and back in trucks to collect specimens for the Smithsonian Institution and to test desert survival procedures.
In 1999 Jamie Clarke became the first Westerner to cross the Empty Quarter of Arabia in fifty years. His team of six, including three Bedouin, spent 40 days crossing the desert with a caravan of 13 camels.
On 25 February 2006, a scientific excursion organized by the Saudi Geological Survey began to explore the Empty Quarter. The expedition consisted of 89 environmentalists, geologists and scientists from Saudi Arabia and abroad. Various types of fossilized creatures as well as meteorites were discovered in the desert. The expedition discovered 31 new plant species and plant varieties, as well as 24 species of birds that inhabit the region, which fascinated scientists as to how they have survived under the harsh conditions of the Empty Quarter.
In 2012, Alastair Humphreys and Leon McCarron pulled a specially designed cart from Salalah to Dubai. They produced a documentary film about their journey and how it compared to those of Wilfred Thesiger 
On 4 February 2013, a South African team including Alex Harris, Marco Broccardo and David Joyce claimed that they became the first people to cross the Empty Quarter unsupported and on foot, in a journey which started in Salalah and lasted 40 days, eventually ending in Dubai. But about their route, there is possibility of controversy. The team only made use of three water stops along the journey, and pulled a specially designed cart which housed all the supplies necessary for the entire expedition.
In 2013 from 18 February to 28 March, South Korean explorer Young-Ho Nam led a team (Agustin Arroyo Bezanilla, Si-Woo Lee) on a crossing through the Empty Quarter on foot from Salalah, Oman, to Liwa Oasis, United Arab Emirates. The crossing was performed with permission from the governments of Oman and UAE. Dewan Ruler's Representative for Western Region, Emirate of Abu Dhabi recognized it as the world's first on-foot crossing of the Empty Quarter.
- In Nelson DeMille's 2012 best-seller, The Panther, U.S. agents hunt down a terrorist to Rub' al Khali, and main character John Corey jokes that "The Empty Quarter" isn't a great name if promoting tourism.
- The desert features in H.P. Lovecraft's Call of Cthulhu: "Of the [Cthulhu] cult, he said that he thought the centre lay amid the pathless desert of Arabia, where Irem, the City of Pillars, dreams hidden and untouched."
- Rub' al Khali is one of the settings for the PlayStation 3 video game Uncharted 3: Drake's Deception, in which protagonist Nathan Drake searches for the Iram of the Pillars.
- The Empty Quarter plays an important role in Clive Barker's Jericho, and in his novel Weaveworld, and in Tim Powers' Declare.
- It also serves as the site of Machine City, Zero-One, in the Matrix series.
- Gerald Seymour's novel Unknown Soldier is almost entirely set in the Rub' al Khali.
- Jack Higgins sets much of the action in his novels Edge of Danger and Midnight Runner in the Empty Quarter.
- The Empty Quarter is also mentioned several times in The Black Stallion series of books from Walter Farley.
- Much of the SIGMA Force book Sandstorm by James Rollins takes place in the Empty Quarter.
- The Empty Quarter serves as the setting of the fictional "Ocean of Fire" horse race in the 2004 film Hidalgo. Filming of the movie actually occurred at various locations in the U.S.A. and Morocco.
- In the Japanese light novel series Zero No Tsukaima, Rub' al Khali is thought to be the place of origin of the main character, Hiraga Saito.
- In Daniel Easterman's second novel, The Seventh Sanctuary it is the location of the lost city of Iram, where the eponymous seventh sanctuary is situated.
- The Fremen people of Frank Herbert's novels on Dune are said to stem from tribes of the Rub' al Khali.
- Josephine Tey's novel The Singing Sands (1952) investigates the murder of a young man who believes he's discovered the fabled city of Wabar while flying over the Rub' al Khali.
- In Daniel Silva's novel Portrait of a Spy.
- It is the site of Hammond Innes's novel, The Doomed Oasis. Innes travelled to Saudi Arabia to research for this book.
- In season two of the Japanese animated series Mobile Suit Gundam 00, one cell of the anti-government force "Kataron" operates from a hidden base in Rub' al Khali.
Astronaut photograph highlighting a part of the Ar Rub' al Khali near its south-eastern margin, in Oman.
Sunset in Rub' al Khali in Saudi Arabia
|Wikimedia Commons has media related to Rub' al Khali.|
- Peter Vincent (2008). Saudi Arabia: an environmental overview. Taylor & Francis. p. 141. ISBN 978-0-415-41387-9. Retrieved 22 August 2010.
- Clark, Arthur (June 1989). Amdt, Robert, ed. "Lakes of the Rub' al-Khali". Saudi Aramco World 40 (3): 28–33. ISSN 0003-7567. Retrieved 22 August 2010.
- "Arabian Desert and East Sahero-Arabian xeric shrublands". Terrestrial Ecoregions. World Wildlife Fund. Retrieved 22 August 2010.
- Van Beek, G. W. (1958). "Frankincense and myrrh in ancient South Arabia". Journal of the American Oriental Society 78 (3): 141–152. JSTOR 595284.
- Thomas, B. (1993). "Ubar—the Atlantis of the sands of rub' Al Khali". Journal of the Royal Central Asian Society.
- Fisher, J.; Fisher, B. (1999). "The use of KidSat images in the further pursuit of the frankincense roads to Ubar". IEEE Transactions on Geoscience and Remote Sensing 37 (4): 1841–1847. doi:10.1109/36.774697.
- Ted A. Morris. "US Air Force Air Sea Rescue in Saudi Arabia 1950-1951". Zianet.com. Retrieved 2011-04-09.
- Everest to Arabia. Clarke J. Azimuth Inc. 2000
- Saudi Geological Survey. "Desert Studies". Retrieved 2011-10-28.
- "Feature Report- 17 March- Empty Quarter Expedition". City 7 News.
- empty quarter expedition website
- Kyu Dam Lee. "ExWeb interview with Young-Ho Nam, life is like crossing a desert". ExplorersWeb.
- Lost city under the Rub' Al-Khali, Saudi Life.
- Sights & Sounds: The Empty Quarter: A National Geographic virtual tour in the Empty Quarter.
- Rub' al-Khali Encyclopædia Britannica
- Clear picture of some of the dunes in the Empty Quarter.