That's why all of the Elemental Planes in my world bleed into one another. You can find earthmote islands floating in the Elemental Plane of Air, volcanos throughout the Elemental Plane of Fire, pockets of air in the Elemental Plane of Earth, and so on. The idea of planes of existence comprised entirely of one of the four classical elements is cool . . . but really doesn't work that well as an adventuring location, which is really how most planes of existence should function (except the Far Realm).