Geological Background of the Nizzana Area

The main purpose of this chapter is to briefly review the recent geological history of the western Negev desert, focusing on the different stages of sand incursion during the Quaternary era and their effects on the drainage system. The Nizzana watershed represents the major system draining the Negev Highlands towards the Sinai Peninsula in the northwest. It extends over 805 km2. The two main tributaries, in the proximity of the sandy area, are the Lavan and Shunra basins (Fig. 1.1), extending over 329 and 220 km2 respectively. From a physiographic point of view, the area is constituted by three distinct belts trending SW–NE (Fig. 1.1).

• 1. The rocky belt. This belt forms the upper reaches of the Nizzana basin (Negev Heights, Matred-Avdat Plateau and Qetef Shivta), composed of extensive rocky outcrops of Cenomanian to Eocene formations.

• 2. The alluvial belt. The western margins of the rocky areas are represented by a large belt of alluvial fans overlying marine sediments attributed to the Miocene- Pliocene period. The assumed location of the Pliocene shoreline coincides with the western limit of Mt Qeren (Fig. 1.1).

• 3. The sandy belt. The Haluza-Agur sand field forms the third unit, dated as Upper Pleistocene. The Mt Qeren anticlinal (Fig. 1.1) separates the alluvial belt from the Haluza-Agur sand field, which represents the eastern sector of the extensive Sinai erg in Egypt.