The mental one is where you imagine the rock and then imagine green wire (which is your chi) connecting itself to the rock. Also thrust your fist at the ground and use telekinesis, guide the telekinetic energy to the gravel you want to bend. : Earthbenders create a wave of earth that they ride on and use as a form of transportation, They can also force a wave of earth outwards, and use it as an extremely powerful offensive attack. Perhaps searching will help.