^The same way you move anything: Leverage, torque and the appropriate application of force.
I'm sure if aliens did visit, they would have had better things to do with their time than move rocks around for the crazy bald ape people.
I can't see how you can lift a 80 tonnes rock with a wooden leverage with out it breaking in to peaces.
We are talking about simple wood here, right?
Legion, i am just trying to understand. If you have some knowledge on how they did it, i would very much like to read about it as well.