Erg Tiffernine
Erg Tiffernine is a sand sea in the Sahara located in the Illizi Province in southeastern Algeria.
Formation and evolution
At the end of the Pliocene epoch, around 2.5 million years ago, when the Sahara had a humid tropical climate, the waters of the Tassili n'Ajjer massif carried large amounts of rock material down its northern slope towards the basin of what would become Erg Tiffernine, where it was deposited as sand. During the Pleistocene, around 1.6 million years ago, the erg began to form during periods of drought. This phenomenon also occurred during periods of drought in the Holocene, until around 3,000 years ago. The dunes were formed by the wind, which sometimes blew much stronger than today in previous eras, forming large complex dunes in the Erg Tiffernine, which is no longer possible with current wind conditions. During these periods, considerable amounts of sand were also transported from the north, particularly from the southwestern part of the Grand Erg Oriental. Initially, longitudinal dunes formed in the direction of the prevailing wind, coming from the north. Later, the wind regime changed and star dunes, which form when winds are weaker and more changeable, appeared on the longitudinal dunes. On the flanks of these compound dunes, other smaller dunes formed, which are mobile. In addition, other dunes formed in the spaces between the longitudinal dunes, interrupted by sebkhas, so that a network-like structure developed in the southern half.Topography
With an area of approximately 4,800 km². Erg Tiffernine is an extension of the much larger Erg Issaouane to the east, to which it is connected by a narrow corridor approximately 16 km wide.Erg Tiffernine has a characteristic amphora shape, making it easily identifiable on satellite images. It extends approximately 150 km from north to south and reaches a maximum width of 47 km. To the southwest, south, and east, the erg is framed by the westernmost foothills of the Tassili n'Ajjer massif. To the northeast, it extends into the Erg Issaouane. The northwest boundary is formed by the wide Oued Igharghar.
The surrounding area and the rocky base of the Erg Tiffernine have an altitude of between 400 and 530 m. The dunes that have formed there are the highest in the entire Sahara, reaching heights of up to 420 m. The volume of sand in the erg is approximately 340 km³. Spread evenly over the entire surface of the erg, this would give a height of about 70 m. The fact that such quantities of sand have accumulated here is also due to the fact that the flanks of the mountains that frame the erg from the southwest to the northeast act as a funnel without drainage. Under the prevailing wind conditions, this has created a situation of congestion for the sand. This is why its sediment balance is positive.
The highest dune ridges reach 870 m. Inside the erg, numerous deep depressions without drainage have formed, without sand cover, whose altitude corresponds to that of the erg's frame. It is clear that there is no elevation of solid ground under the sand dunes of the Erg Tiffernine.