Over a few million years apparently you get shaken by an earthquake many hours in the Attacam desert. Pretty cool story. Safe for work link.
http://www.msnbc.msn.com/id/44862961/ns/technology_and_science-science/t/rocking-discovery-boulders-rub-shoulders-during-quakes/
Fascinating.
It has me wondering if there are any formations they’ve found with this kind of rock embedded and never made the connection before.