GC70YQ8 Bassata Dunes (Earthcache) in United Arab Emirates created by Silberschakal

GC70YQ8 ▼

A cache by Silberschakal Message this owner

Hidden : 2/15/2017

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Size: Size: other (other)

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Geocache Description:

Bassata Dunes

Bassata Dunes is an area of interesting sand dunes near Bassata Desert Village in Ras al Khaimah, United Arab Emirates. Bassata means "Simplicity" in Arabic, which is reflected all over this desert camp, giving you an insight on the traditional Arabic desert life of the earlier days.

Aeolian dunes

Aeolian dunes are hills of loose sand built by the wind. According to their shapes they are splitted into crescentic or transverse dunes, lunettes, linear dunes, star dunes, dome dunes, parabolic dunes, longitudinal (seif) dunes and reversing dunes.
The typical forms of dunes which can be observed near Bassata Village are linear dunes and longitudinal (seif) dunes.
Linear dunes are straight or sinuous sand ridges formed diagonally or horizontally to the wind direction. They are typically much longer than they are wide. Some linear dunes merge to form Y-shaped compound dunes. Often they form in bidirectional wind regimes. The long axes of linear dunes extend in the resultant direction of sand movement.
Seif dunes (after the Arabic word for "sword") elongate parallel to the prevailing wind, possibly caused caused by a larger dune having its smaller sides blown away. They are common in the Sahara (North Africa) and Rub' al Khali (Arabian peninsula). Seif dunes are thought to develop from barchans if a change of the usual wind direction occurs. The new wind direction will lead to the development of a new wing and the over development of one of the original wings. On a seif dune the slipface develops on the side facing away from the strong wind, while the slipface of a barchan faces the direction of movement.
The sand mass of dunes can move either windward or leeward, depending on if the wind is making contact with the dune from below or above its apogee. If wind hits from above, the sand particles move leeward, if sand hits from below, sand particles move windward. The leeward flux of sand is normally greater than the windward flux.

Ripple marks

The sand of the dunes often shows ripple marks (wind ripples), these are sedimentary structures indicating the agitation by wind. Aeolian processes form different types of ripple marks. Normal ripples, also known as impact ripples, occur in the lower part of the lower flow regime sands with grain sizes between 0.3 to 2.5 mm. They have straight or slightly sinuous crests approximately transverse to the direction of the wind and form wavelengths of 7 to 14 cm. Megaripples occur in the upper part of the lower flow regime with bimodal particle size. They form long wavelengths of 1 to 25 m where the wind is not strong enough to move the larger particles but strong enough to move the smaller grains. Fluid drag ripples (aerodynamic ripples) are formed with fine, well-sorted grain particles accompanied by high velocity winds which result in long, flat ripples.

Your task to log this Earthcache as found:

Answer the following questions in your own words and send me the answers via message to my profile:

1.) What do you think, in what direction do the dunes move?

2.) Has the moving of the dunes any influence on vegetation?

3.) The sand's colour is brownish-red. Looking closer to the sand grains, what different colours can be observed? What size do you estimate the grains?

4.) Estimate the wavelength of the ripple marks! What type of ripples can be observed here?

5.) Optional: If you like, you are warmly invited to add a picture of you / your GPS at the location to the log!

You can log immediately after you sent me the answers! There is no need to wait for a log permission! I'll contact you if there's something wrong.

Have fun and enjoy!

Sources:

Bagnold, R. (2012): The physics of Blown Sand and Desert Dunes.
Goudie, R. C., Warren, A. (1996): Desert geomorphology.
Parsons, A. J., Abrahams, A. D. (2009): Geomorphology of Desert Environments.
wikipedia.org

All pictures were taken by the author.

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