Taurus, Virgo, Capricorn. The signs concerned with what can be held, sorted and kept.
Earth signs sit at 30°, 150° and 270°, again a division by three, again mutually trine. Taurus holds what spring produced, Virgo sorts what summer grew, Capricorn endures what winter leaves.
Every element contains one cardinal, one fixed and one mutable sign, so an element is never a single temperament — it is one substance in three states. Capricorn opens a season, Taurus sits in the middle of one, Virgo ends one.
Earth is the element most closely tied to the second, sixth and tenth houses in the traditional scheme — resources, work, vocation — because whole-sign charts with an earth sign rising place the other two earth signs on exactly those cusps.