In the Elemental Body line of spells, it states you gain "push" when you transform into an earth elemental. The only problem is... Earth Elementals don't have push in the Beastiary. I'm sure this is an oversight--- in my games I plan on ruling it this way:
Small and Medium earth elementals push 5'.
Large earth elementals push 10'
Huge (and elder) earth elementals push 15'
Alternatively, I would just treat it as a free bull rush with CMB = the attack roll and resolve the bull rush as normal. I'm leaning much more heavily towards the second interpretation currently, even though push now indicates it's a fixed distance. My reasoning is that grab acts as a free grapple attack with CMB = attack roll, so having push operate as a bull rush in the same manner seems balanced to me.
i Remember reading about this somewhere else but can't remember where or if an official answer was given. i think the plan was to give earth elementals "push" but they were given earth mastery instead. im not sure if elemental body still provides push. if it does "push" is still listed in the back of the bestiary if you want to know what it does.
This was posted by James Jacobs on a thread on the same topic.
Easiest fix: earth elementals don't get push, and neither do spellcasters who use elemental body I.
Actual errata for it is still pending Jason's input.