precious-postcards

Purnululu National Park

The 239,723 ha Purnululu National Park is located in the State of Western Australia. It contains the deeply dissected Bungle Bungle Range composed of Devonian-age quartz sandstone eroded over a period of 20 million years into a series of beehive-shaped towers or cones, whose steeply sloping surfaces are distinctly marked by regular horizontal bands of dark-grey cyanobacterial crust (single-celled photosynthetic organisms). These outstanding examples of cone karst owe their existence and uniqueness to several interacting geological, biological, erosional and climatic phenomena.

http://whc.unesco.org/en/list/1094

Purnululu National Park is famous for the sandstone domes, unusual and visually striking with their striping in alternating orange and grey bands. The banding of the domes is due to differences in clay content and porosity of the sandstone layers: the orange bands consist of oxidised iron compounds in layers that dry out too quickly for cyanobacteria to multiply; the grey bands are composed of cyanobacteria growing on the surface of layers of sandstone where moisture accumulates.

http://www.worldheritagesite.org/sites/purnululu.html