Definition
A naturally occurring rock mass that is balanced on a bedrock pedestal. The rock mass is typically detached from its pedestal by a horizontal to subhorizontal joint or discontinuity.
Description
Balanced boulders are ubiquitous features in arid landscapes. On Earth, they are typically balanced on bedrock pedestals throughout upland drainage basins and pediments (Fig. 1a – PBR landscape), range from a few decimeters to several meters across, and can weigh up to several tons (Fig. 1b – example photo of a PBR). On Mars, numerous perched rocks have been found in Gusev crater (Greeley et al. 2006) and at the landing site of Pathfinder (Lucchitta 1998).
(a) Example of a typical granitic landscape (background) in which balanced boulders form and a precariously balanced rock (foreground) from Arizona, USA (Copyright 2010 David E. Haddad). (b) Example of a granitic...
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References
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Haddad, D.E., Arrowsmith, J.R. (2014). Balanced Rock. In: Encyclopedia of Planetary Landforms. Springer, New York, NY. https://doi.org/10.1007/978-1-4614-9213-9_467-1
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DOI: https://doi.org/10.1007/978-1-4614-9213-9_467-1
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