Primary gypsum nodules in a modern sabkha on the Mediterranean coast of Egypt. Desert Roses - Gypsum Crystals Large desert roses or gypsum sand crystals in the sand of a supratidal sabkha at Umm Said in eastern Qatar. They split and fan open along these characteristic cleavage planes of gypsum. The four-wheel drive car, which has just dropped me, has driven over one low horn and is now heading for the high avalance lee face. Depending upon how near they are to the coast these large sand-dunes in southern Qatar either migrate into the sea, extending a sabkha, or move on into Saudi Arabia and the great Rub' Al Khali or Empty Quarter.
Dunes can migrate at a rate of several metres a year.
The flat area to the left of the car is a sand sabkha. Let us have a look at a section through part of a similar barchan but in a different desert locality. We have arrived at a sand quarry in an unconsolidated dune. The floor of the quarry is the damp sabkha surface, on which I am standing. Yes, you can see it ties in with the direction of the prevailing Shamal winds blowing down the Arabian Gulf from the north-west.