Nullarbor (Environmental Region 7.6)
This region consists of six environmental associations. It includes the Nullarbor Plain and adjoining undulating plainland to the east. The Nullarbor Plain is a structural limestone plain in which sub-surface erosion has led to the development of widely scattered dolines and cave systems. A spectacular cliffed coastline with cliffs to 100 m high abruptly truncates the plain at the Great Australian Bight. Shallow red calcareous loams or earths occur on the limestone and carry a low shrubland of saltbush, bluebush and samphire with some open mallee in the area fringing the Bight. The plain east of the Nullarbor is formed mainly on calcarenite and calcrete and has considerably greater relief. Brown calcareous earths are the dominant soils and carry mallee with a saltbush understory. Aeolian sand sheets and dunes with a different type of mallee cover parts of the plain which, in the north, merges with the Great Victoria Desert. Long sandy beaches and occasional cliffed headlands occur along the coastal margin of this plain. Foreground and middleground panoramic views predominate in the east of the region, broadening to background panoramic views on the Nullarbor Plain, where only minor topographic features relieve the vast expanse of saltbush-bluebush country. The focus of scenic interest lies at the coast, where long sandy beaches or cliffs are impressive features. The climate is mild to hot in summer and cool to cold in winter with very low and unreliable rainfall and high evaporation throughout the year. Mean annual rainfall decreases from 300 mm on the coast in the south to less than 150 mm in the north, while mean annual evaporation increases from 2400 mm to 3000 mm over the same area. Mean monthly evaporation reaches 400 mm in summer and exceeds the 90th percentile of monthly rainfall throughout the year. Temperatures show high diurnal and seasonal variation.