I'm sure the shugenja from
Rokugan have elemental school specializations. In the setting they are divine spontaneous casters, but also the only caster class.
They don't really have anything especial 'earthy', mostly they simply
have to learn a majority of earth-oriented spells, although in Rokugan also spells with a 'philosophical' tie to an element are legit. Couple this with the general inability to learn spells of the opposite element, and you can see that an (obligatory) specialization is actually more of a limitation than a boon

You did get free Spell Focus and the minor ability to 'sense' your element, but nothing really special.
But all in all, this is actually good news, because those Shugenjas do feel quite a lot 'elemental' just because they know (and use) a lot more spells of their chosen elements than any other spell. And this actually means you don't really
need any unique class or subclass to create an 'earth' spellcaster! All you need is the following:
- play a
Wizard
- pick spells that have a
direct 'earthy' nature (
Stoneskin,
Wall of Stone,
Passwall,
Earthquake...)
- look also for spells that have an
indirect or 'philosophical' tie, e.g. spells that grant endurance, strength, physical protection, slow down enemies...
- refluff all other spells!
Magic Missile could take the shape of flying rocks,
Mage Armor could make a layer of stone appear around your body etc.
- as for the subclass, if nothing is good enough, take the least inappropriate (maybe Transmutation)