The Empty Quarter (Rub' al Khali in Arabic), has the world's largest expanse of unbroken sand, encompassing the southern third of the Arabian Peninsula, including southern Saudi Arabia, and areas of Oman, the United Arab Emirates and Yemen. The desert covers some 250,000 square miles (the area between 44°30'-56°30'E., and 16'30'-23°00'N). The Empty Quarter is 1200 km long and 650 km wide, and is among the largest continuous deserts in the world.
Patterns of sand dunes vary with wind direction, with both seasonal and occasional variations having an effect on the shape of a dune. Also with large sand dunes the wind directions from the past can play an important part in the shape of a dune and their orientation with respect to present wind directions.. In the case of the empty Quarter sand dunes have developed from the end of the last ice age which was more than ten thousand years ago.
There are Five major types of dunes.
Barchan dunes
are crescent-shaped dunes that are concave downwind. They form where there is limited sand and a constant wind direction.
Parabolic dunes
are a crescent shaped dune that is concave upwind and forms in areas in which there is some vegetation and a good supply of sand.
Longitudinal dunes
are linear dunes that are parallel to the direction of the wind and forms in areas in which the wind direction is not constant and the supply of sand is moderate to good. Longitudinal dunes can be kilometers in length. They are formed in areas in which there is a desert pavement and variable winds.
Transverse dunes
are linear dunes that are perpendicular to the direction of the wind and are not as long as longitudinal dunes. Transverse dunes form in areas with abundant sand and little vegetation.
Dome dunes
are circular to oval mounds of loose, well-sorted, very fine to medium sand. Simple dome dunes are only a few meters in height and decimeters in diameter. They do not have slipfaces.
Moreeb Dune is billed as the tallest in the UAE and is about 300mtrs high.
Most dunes have a “slipface” and in general the slipface angle can vary from about 30 degrees to 60 degrees.
In your email estimate the angle of the slipface and say what it is being used for at the present time.
When one looks at a satellite picture of the area the sand dunes are interspaced with areas of “Silver” These silver areas are “Sabkha”
Sabkha is the Arabic term for low lying flatlands – in this case Interdunal Sabkha.
Sabkha is always very close to the local water table. ( Strange indeed in the desert) Groundwater is drawn towards the surface by capillary action and evaporates in the upper subsurface in response to the high temperatures. There it deposits dissolved salts, including calcium carbonate, gypsum (CaSO4-2H2O), anhydrite (CaSO4) and sodium chloride or halite (NaCl), which precipitate in that order. These salts create a hard, impermeable crust in a zone about half a meter below the surface. This crust, along with high salinity, discourages all plant growth and makes it dangerous to drive on as the crust is likely to give way.
However at Moreeb dune you can drive on it. In your email say why .
===In order to log this cache you need to post a photo of your team and your GPS at the location with Moreeb Dune in the background.===
Additionally you need to answer a few questions and email the owner with the answers.
=== To summarize the email requirements.===
1. What type of dune is Moreeb Dune (Barchan, Parabolic, Longitudinal, dome or Transverse)
2. Estimate the angle of the slipface and say what it is being used for at the present time.
3. Why can you drive on the Sabkha at Moreeb Dune ?
 Kid Friendly  Wheelchair Access  Dogs Allowed
 Available year-round  Restrooms available
 Water Available
 Off-trail Hiking Recommended  Scenic View  Offroad Vehicles Allowed |
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