Landscape :
Most of the field study area consists of a plateau of basalt flows and weathered boulders overlying limestones and sandstones. Lying at an altitude of around 800m. this rolling landscape is punctuated with dormant volcanic vents.Mineralisation associated with the vents reveals deposits of zeolite, porcellanite, and bentonite. Where there is a depression water may appear at the surface as at Azraq (see Hydrology). Winter snow melt and spasmodic rainfall have created a pattern of wadis, some of which converge onto internally draining basins where evaporation results in dusty sandy-clay surfaces (qa’a). Where these deposits are coarser the surface is described as marab. The major source of the basalt is the Jebel al-Arab across the border in Syria. The upper layers have been heavily weathered into football size boulders, which more often than not display lichen growths on their damper northern sides. The landscape takes on a patchwork appearance owing to the clearance of the boulders by the Bedouin over many years attempting to provide crude soils for vegetation growth.
Driving east from Amman the overwhelming appearance is of wide, open stony and rocky surfaces broken only by the appearance of the man-made desert castles. On the descent into Azraq the appearance changes to a more vegetated basin in part because of the proximity of water to the surface, in part owing to the creation of fields growing a variety of crops. Eastward from Azraq the open, rolling nature starts again and continues virtually to the Iraqi border. Towards the south and the Saudi Arabian border however the basalt peters out to bring the underlying rocks to the surface. The El Adahaek basin is rimmed with sandstone escarpments and filled with dunes of various sizes together with rocky, deflated outcrops (gour).
Climate:
This is a desert of extremes. Being so far in land it experiences cold, often snowy, winters and blisteringly hot summers with daytime temperatures sometimes as high as 46oC. Diurnal ranges are high too. The rainfall is variable according to location. In the higher regions of the north and west the precipitation my reach 250mm but to the south near the Saudi border it may be less than 50mm. To view Jordan’s climate data visit the website of the Jordan Meteorological Department.
