Starfish Dunes EarthCache
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When you visit the area of Northern Oman known as the Starfish Dunes then you too will spot the larger than average pyramidal dunes that are scattered through this part of the world. We were fascinated by their beauty and determined to find out why they form here and what caused them.
The Rub Al Khali (the Empty Quarter) covers much of the south-central portion of the Arabian Peninsula, and with an area of approximately 660,000 square kilometres (quarter of a million square miles) it is the largest continuous sand desert on Earth.
The sand dunes of wind-blown deserts occur in a variety of shapes, which reflect differences in prevailing wind directions. Viewed from space the long linear dunes of the Rub Al Khali begin to break up into isolated large star shaped dunes in the northeast and east. This is most likely the result of both wind pattern interactions and changes in the sand supply to the dunes. This part of the Rub Al Khali is close to the Hajar Mountains and is known as Starfish Dunes. They are located in Northern Oman close to the UAE border and are for the most part reddish-brown, linear sand dunes alternating with blue-gray stony flats like dried lake beds.
The major trend of the linear dunes of the Empty Quarter is transverse to north westerly trade winds that originate in Iraq (known as the Shamal winds). However it is the south westerly winds that occur during the monsoon season (Kharif winds) that cause the formation of secondary dunes with crests radiating in several directions originating from a single point, looking very like a starfish, hence this areas name. These star dunes typically have slip-faces on three or more arms that radiate from the high centre of the mound and due to the varying winds tend to grow upward rather than laterally.
Star shaped dunes can also be found in other deserts of the world such as the Sahara, the Namib in Southern Africa and the Badain Jaran Desert, China. The last is reckoned to be home to some of the tallest star dunes in the world with some estimated to be over 500m high. When driving in the Starfish Dunes you can often spot these dunes as they invariably stand head and shoulders above the surrounding sand and sabkah. Reaching their summit is often difficult even on foot due to the steep nature of the arms but if you can you'll be rewarded with amazing views. The location of this earth cache is not at a summit but part way up a typical star dune giving views across the Starfish area and of at least one other similarly shaped dune nearby.
- Star dunes are amongst some of the tallest dunes can you suggest why?
- How high would you estimate the dune at GZ or the one opposite to be?
- Can you describe the star dunes of the Starfish area including their shape and colours of their sand?
Finally why not post an optional picture of the star dunes around you at GZ to share their unique colours and shape with everyone.
NB: The terrain here is extremely difficult to access and requires prior desert driving expertise though if you do go you’ll find it very rewarding. As always in the sands of the Empty Quarter plan your trip carefully and go prepared in a group of 4x4 vehicles with sufficient water, fuel and food plus suitable rescue kit.
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