Earth Magic

Earth Magic is known to be the most defensive one of elemental magics, that allows to use ground (easy to find in most places) to to form nearly impenetrable walls to shield magician from incoming attacks. There are also spells that allow to form into 'armors', create traps (similar to moving sands). Most of the trap-spells immobilize rather than dealing damage, and slows down rather than immobilize.
There are also offensive spells, in most cases dealing blunt damage. They can be compared to magical slingshots, with few melee-range spells, most of them dealing morale damage rather than real. This magic tends to be a first choice of magician with simple minds - not stupid, but rather those than prefer to think things through before running in blindly, and are not prone to sudden flashes of inspiration.

Subschools of Earth Magic

Stone Magic [SP] - Stone Magic - on its most basic level - is considered a part of education of stone magicians in the Imperium of Karadia, due to it being required if such magicians wish to deal some actually decent damage to their enemies. It also allows to greatly improve already decent defensive capabilities of Earth Magic, not to mention earth elementalists versatility (where you can't find earth, you will surely find stone). Magician proficient in this magic will become a potent power on the battlefield, capable of rising stone wall from nowhere (if only not for some time) or throwing stone projectiles/lances towards their enemies.
Granite Magic[SP] - Granite Magic is a fusion of Stone Magic with certain transmutation technics, allowing its wielders to change the stone they are using in their spells into other types of rock. The name 'Granite Magic' hails from the fact that granite - with its toughness and general resistance - being one of the first types of rock the magicians (mostly closing on the archmage title, due to power and control requirements of the Granite Magic) learn to transmute. There are even certain magicial types of rocks, allowing for variety of special effects.