Atacama Desert Soil Microbiology.

The Atacama Desert is an ancient temperate desert (mean annual temperature of 14-16°C) that extends across 1,000 km from 30°S to 20°S along the Pacific coast of South America (McKay et al. 2003; Fig. 6.1). As discussed by Rundel et al. (1991) and Miller (1976) the desert owes its extreme aridity to the climatic regime dominated by a constant temperature inversion due to the cool north- flowing Humboldt Current and the presence of the strong Pacific anticyclone. The position of the Pacific anticyclone is generally stable with a small shift of a few degrees south in the summer (Trewartha 1961). Geological and soil mineralogical evidence suggests that extreme arid conditions have persisted in the Southern Atacama for 10-15 million years (Myrs; Ericksen 1983; Houston and Hartley 2003; Clarke 2006) making it one of the oldest deserts on Earth. [ABSTRACT FROM AUTHOR]