Geomorphological Map of the Tadrart Acacus Massif and the Erg Uan Kasa (Libyan Central Sahara)

Abstract

Here we present a geomorphological map of the Tadrart Acacus Massif and Erg Uan Kasa (SW Libya, central Sahara). The geomorphological mapping of the area was carried out by means of satellite imagery analysis followed by detailed control of units in the field. The Tadrart Acacus is a sandstone massif delimited to the West by a high scarp and cut by a dendritic fossil drainage network of W-E-oriented wadis. The massif has been shaped since the Tertiary by etchplanation and solutional processes; the latter is demonstrated by the ruiniform landscape and the high number of caves and rock shelters that dot the vertical cliffs of the wadis. To the East, the Tadrart Acacus merges below a complex system of sand ridges that form the Erg Uan Kasa. The large interdune corridors of the sand sea are dotted by lake sediments, which formed during the Pleistocene interglacials and the African Humid Period of the Holocene, when piezometric lakes were sustained by intense monsoonal rainfall. Geomorphological investigation demonstrates that the extant landscape originated thanks to the overlap of surface processes triggered by divergent (humid/arid) environmental conditions.

Holocene Supra-Regional Environmental Changes as Trigger for Major Socio-Cultural Processes in Northeastern Africa and the Sahara

“…The level of piezometric lakes in the interdune basins of the Edeyen of Murzuq in the Libyan Central Sahara fell at ca. 8.1-8 cal kyr BP (Cremaschi and Zerboni 2011;Zerboni and Cremaschi 2012), suggesting a persistent interruption in monsoon rainfall, which also caused the desiccation of springs in the Tadrart Acacus massif (Cremaschi et al 2010;Zerboni et al 2015). A single but wellconstrained record from western Nubia illustrated a similar trend: the palaeolimnological record of Lake Gureinat (Hoelzmann et al 2010).…”

“…Progressively, the climate grew hotter and drier, and while in some areas, particularly highlands, conditions remained more humid than at present (di Lernia 2002;Drake et al 2008), the majority of lowlands desiccated as lakes dried; by ca. 5.5 kyr cal BP present-day arid-climate vegetation was established (Cremaschi 2002;di Lernia 2002;Zerboni et al 2015). In the Messak-Murzuq region, under environmental conditions marked by high seasonality and progressive deterioration, rituals centred primarily on bovines emerged.…”

Geomorphology of Mount Ararat/Ağri Daği (Ağri Daği Milli Parki, Eastern Anatolia, Turkey)

“…As commonly attested in arid and semi-arid regions (Zerboni, Perego, & Cremaschi, 2015), due to the almost complete absence of arboreal vegetation and with a scarce herbaceous coverage restricted to lower elevations, the morphological features can be investigated using satellite images in the visible spectrum. High-resolution images are the most suitable for recognizing and mapping geomorphological units: we chose to detect landforms on PLEIADES (spatial resolution: 0.5 m), SPOT 7 (1.5 m), and Google Earth™ (∼2 m) imagery.…”

Geomorphology of the Jebel Qara and coastal plain of Salalah (Dhofar, southern Sultanate of Oman)

“…The geomorphological mapping of the region is based on data retrieved and interpreted from both remote sensing imaging and field observations, according to the approach proposed by several authors for mapping arid and semi-arid regions (Azzoni et al, 2017;Hüneburg et al, 2019;Perego, Zerboni, & Cremaschi, 2011;Zerboni, Perego, & Cremaschi, 2015). Validation of the desk-compiled map was done during several field surveys, which included a few kilometres of buffer beyond the northern watershed of the Jebel Qara.…”