Does Poseidon actually have dominion over the ground in the books?  I won't claim to be a Greek Mythology expert, but that makes very little sense to me from a logical point of view.  He's the god of the sea, as in water and storms.  What do earthquakes have to do with the sea?  Is that something from actual mythology or did Riordan take some artistic liberties?<br/><br/>The earth (as in rocks and dirt, earthquakes etc) sounds much more like Hades' deal.  It's even in their list of powers... ie Geokinesis.<br/><br/>I'm not knocking it, just curious.  Are earthquakes technically the domains of two of the gods?