United Arab Emirates : Alluvial Fans and Dunes
I attended the 4th Alluvial Fans workshop in Ras Al Kaimah in December 2012. As well as some nice alluvial fans and opheilites in the Oman mountains, the conference field excursion also included some spectacular linear dunes and belts of barchans near the Oman border in the south of the UAE, at the edge of the Rub' Al Khali desert. After the workshop, Jani Radebaugh and I took the opportunity to visit the striking megabarchans south of the Liwa Oasis belt. Some highlight photos are below. Jani's web page has many more pics
Dubai is a neat city, with a mix of old and new. The Burj Khalifa is impressive, as it was designed to be, and rather pretty at night |
The planetary contingent at the Alluvial Fans workshop : Jani, myself, Tjalling de Haas and Germari de Villiers. A nice alluvial fan in the background - note the dark varnished rocks on the top surface of the fan deposits. |
In the Oman mountains on conference field trip. Remarkable folded limestone in the background. Nicely rounded cobbles of alluvial deposit in foreground |
I was intrigued by this texture in some boulders, caused by rain eating into the limestone. The nice radial pattern implies that this face has been uppermost and unmoved for some time. |
Interdune deposits had some white limestone or gypcrete : here Jim Driscoll and Ann Mather, one of the conference organizers, assay the saltiness of the rock to help diagnose its composition. |
Between the linear dunes, belts of barchans cross the flat floor. |
A couple of parallel linears are visible in the distance: in the foreground some barchans show nicely against the white floor. The Oman border fence and (unmanned) observation tower give this image a real 'Star Wars' other-worldliness |
I brought along my HERO kite camera (and two kites, one for strong winds, and a larger one for weak ones) to get aerial shots of the landscape. This view of a barchan belt - note that these barchans may periodically reverse : they do not quite have the classic shape. |
North of Liwa is a wide belt of barchanoid transverse ridges. |
We tried the kite here - nice little barchans |
At Liwa the megabarchans are marching onto date plantations. Here a bit south of the oasis there are no dates, just a few camels. The megabarchans were difficult to mentally process as dunes - too big, they just seemed like mountains. |
Although a bit tricky to see due to the wide angle lens, this kitecam pic shows the steep megabarchan face at left, and the superposed barchan/transverse dune forms on the megabarchan crest. |
On the valley floor, at the edge of the barchan stream, a few small dome dunes were present. If/when they grow larger, they mau develop a slip face, like a proper barchan. |
While exploring the slipface of a megabarchan (a sheer climb behind me, some 50 meters or more) some locals stopped to say hello - they had their handsome falcons with them to do some hunting |
We did some recreation of our own. The quad bikes rented by the hotel were sadly underpowered, but fun to ride at least a bit on the sand |