The “Piedra Movediza” (“Rocking Stone”) of Tandil (Province of Buenos Aires, Argentina) and the “Piedras Equilibristas” (“Balancing Rocks”) of Paraguay and Brazil

The “piedras movedizas” (named as “rocking stones” in English) and the “piedras equilibristas” (in English: “balanced rocks”) are large blocks and boulders naturally and delicately balanced over one or more supporting points on the same or different bedrock types. These particular landforms are usually residual “corestones”, formed by deep chemical weathering processes and later exposed due to fluvial and pluvial denudation. These stones were named as “balanced rocks” by Fairbridge (1968). These “piedras movedizas” (“rocking stones”) are known from many different places in the world, but in South America they are mostly related to ancient Gondwana Landscapes. This paper discusses the genesis of the “Piedra Movediza” of Tandil, Buenos Aires province, Argentina, and compares it with two other spectacular examples of “piedras equilibristas” (balanced rocks) in Paraguay and Brazil.