Earth is an element in Final Fantasy VIII. It is opposed to Wind. Flying enemies typically avoid ground-based abilities, and the player can get the same effect with Float. Many bosses use Quake spells, and so mitigating Earth damage in some manner is a good strategy.
The player can avoid Earth abilities with Float status, and also mitigate/absorb the damage by junctioning spells to Elem-Def-J. The following spells provide Earth protection when junctioned to Elem-Def-J: Ultima, Full-life, Quake, Float, Shell, Life, and Meteor. Out of these, Quake has the best effect (2% per spell) and Shell the weakest (0.2%). The best protection is 100% absorption of Earth damage by junctioning 200% of the Earth element to Elem-Def-J.