Tag Archives: PBRs

Precarious Rocks Give Clues to Future Earthquake Movements

A new approach to predict the intensity and direction of earthquakes lies in an unlikely source — 10,000-yearold, improbably balanced rocks. You’ve probably seen pictures of these; they are astounding, seemingly impossible and a little scary. You certainly wouldn’t want to be standing downhill if they toppled over.

These geological features are called Precariously Balanced Rocks or “PBRs.” They are formed slowly when tectonic forces elevate granite rocks from below ground to the surface, and erosion whittles away the softer surrounding materials leaving the unlikely and amazing result.

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