In Baltic lore, each of the Old Gods has his or her own sign.
For the Sun, it's the Sun Wheel. For the Moon, the Crescent.
Fire is the Fire Cross, the swastika, Thunder, the Thunder Cross, or compound swastika.
The Winds, since there are four of them, have the Cross, Heaven the Mountain. (How else would you draw a picture of the sky?)
But what about Earth?
My teacher, Tony Kelly, of the Pagan Movement in Britain and Ireland, used to say, “If we know anything at all about Earth, we know that she's Mother.”
At the time, as a good, doctrinaire second wave feminist, I found this statement reductionist and objectionable.
Since then, I've changed my mind.
Take a look at Earth's brothers and sisters, the other planets of our solar system. Then look at Earth. What's the difference?
So I think that Earth's symbol is the Wedge, the Delta.
Having independently reached this conclusion, I was pleased to find that Mary Mackey, preeminent novelist of Old Europe, concurs. In her Earthsong trilogy, set among the Copper Age Goddess-worshiping cultures familiarized by the work of archaeologist Marija Gimbutas, the triangle symbolizes Earth, Goddess, and Mother (Mackey 1998, 181).
“The triangle is Her universal sign,” she explains. “It represents the holy triangle of fertility between Her thighs” (Mackey 1993, 119).
The number three is, of course, Earth's sacred number, for her Youth, Maturity, and Age.
But for all her children, Earth, foremost, is Mother.
And her sign is the holy Wedge.
Mary Mackey, The Fires of Spring (1998). Onyx
The Year the Horses Came (1993). Harper