Introduction

The Great Rift Valley (GRV) is a geological phenomenon of global scale, which is of fundamental significance for understanding the evolution of the Earth. It represents a major manifestation of crustal plate tectonics, and the origins and development of oceans and continents.

Geologically the GRV is a realm of superlatives, extending over 7,000 kilometres from Turkey to Mozambique; it is the longest rift valley in the world and among the largest. The Jordan Valley and Dead Sea at 400 metres below sea level is regarded as the lowest point on the earth’s surface and the narrowest section of the rift.

The GRV has been evolving over the past 30 million years. Current evidence of continuing geological evolution is constant seismic activity and volcanism. It is a landward extension of a mid-oceanic ridge system that encircles the globe and is a manifestation of the process of crustal plate divergence. Essentially, the crust is splitting apart and separating the African and Arabian tectonic plates. This process creates a massive tension crack, causing a block of crust to drop down between the diverging crustal plates - geologists refer to this as a horst (raised part) and graben (down-thrown part) system. This phenomenon can be seen at Masada and Qumran exemplifying components of the Dead Sea sector. It is a horst in the western escarpment, with a summit about 400 metres above the surrounding terrain, towering over the Dead Sea that fills the graben. The Makhteshim/al-Ajran in Jordan and Israel are part of a regional tectonic fold belt accompanying the opening up of the Dead Sea Rift Valley.

The Jordan River Valley, part of the Great Rift Valley (GRV), is at the centre of one of the most important bird migration flyways on the globe. An estimated five hundred million birds migrate annually through this narrow corridor between the southern and northern hemispheres. It is also an important migratory route of global avifauna, such as the black and white stork, common pelican, kingfisher, herons, shovelers, sandpipers, shanks, francolins and other globally threatened waterfowls.

Many of these species breed in Central and Eastern Europe and a significant portion of their entire populations pass through the region. Many of these species depend on open spaces, both natural and agricultural, to rest and forage. Others, such as wintering birds of prey, pelicans and storks, and summering bee-eaters and warblers spend an entire season in the region.

This area is also considered an important Middle Eastern wetland; both Birdlife International and Wetland International have declared the entire Jordan River basin a significant bird and wetland area, since it maintains many globally valuable species that are on the IUCN Red List as regionally or globally threatened or endangered species. The freshwater wetlands and the Jordan River Valley's location in a water-stressed region, are the last or first staging post before or after the migratory birds cross a vast expanse of desert. Considering the current trends in wetland protection and management in the Levant, where most wetlands have been drained, or so altered that they are no longer ecologically functional for wildlife, the relative importance of the region's surviving wetlands and rivers can be expected to continue to increase.

The hot, dry Arabah Valley, located in the Jordan Rift Valley south of the Dead Sea, stretches between its northern borders at the Dead Sea to the Red Sea in the south. The Arabah is framed by the Negev Mountains to the west and the Edom and Sharrah Mountains to the east. The sheer, barren mountains rise dramatically from 350 metres below sea level at its northern end to 350 metres above sea level at Jabal Risha, and then descend again to sea level at Aqaba and Eilat. The two parallel mountain chains bordering the Arabah are separated by a corridor of salt marches, sand dunes, and acacia stands. In addition, numerous seasonal rivers (wadis) penetrate the main north-south corridor, creating vital east-west ecological passages throughout the Arabah.

The Valley is comprised of numerous unique and varied habitats including alluvial fans, sand dunes, semi-stable sands, salt marshes, and seasonal riverbeds. The approximately 190 kilometre-long Valley is of outstanding zoogeographical importance due to its position at the focal point of the biological filter between the Palearctic, Ethiopian and Oriental regions. The Valley consists of some 75 square kilometres of sand desert and dunes, including one of the only known habitats with viable populations of several rare and endangered species such as the Sand Cat (Felis margarita), the Sand Fox (Vulpes rueppelli), the Desert Gazelle (Gazella dorcas isabellina), and the Spiny Tailed Lizard (Uromastix aegypticus).