EARTH monsters are powerful cards focused both on brute strength and rock-solid Defense. The Field Spell Card "Gaia Power" is targeted toward Earth monsters, increasing their ATK by 500 but decreasing their DEF by 400. Another Field Spell Card, "Canyon", while it uses Rock-Type monsters, is also good to use, since Rock-Types are nearly all Earth. Earth is usually thought of as the opposite of WIND, though there is no direct advantage other than in certain video games (even if this idea also appears in the effects of some cards like "Desert Twister", "Milus Radiant" or "Bladefly"). In a few other contexts it is also seen as the "neutral" element between DARK and LIGHT, as seen in cards like "Sky Scourge Invicil" and Warrior of Zera.
Earth monsters are not greatly supported by other cards, though they have a few. Those include: "Giant Rat", "Milus Radiant", "The Rock Spirit", "Gigantes" and "Warrior Lady of the Wasteland" for Earth Warriors.
Amazoness cards are all EARTH Warrior-Type monsters, and so can use many of the cards that support Earth types, as well as those designed specifically for Warriors, and specifically for themselves. The "X-Saber", "Cyber Girls" "Iron Chain" and "Ancient Gear" Archetypes are also EARTH.