Distribution and Morphology of the Bedrock Basins Known as Pans in a Granitic Inselberg Landscape

In 2008, Pogue and Katz reported that on granitic exposures in the Cassia City of Rocks, Idaho, the larger pans (shallow flat-floored gnammas or rock basins with overhanging sidewalls) are developed and preserved high in the local relief. They related this aspect of pan distribution to duration of exposure. This working hypothesis is tested by examining pan distribution on granitic inselbergs located on northwestern Eyre Peninsula, in semiarid southern South Australia. Pans in numbers have developed on sensibly level surfaces and have been shaped by pools of standing water. The larger—and more complex—forms are situated high in the local relief, as concluded by Pogue and Katz, but where water supply is limited to direct precipitation, by contrast with lower sites, where rainfall is augmented by runoff.