30 Unusual Archaeological Finds In The US We Still Can’t Explain

26. A SOLAR CALENDAR AS ROCK ART

Astronomy was one of the essential things in culture as our ancestors studied the night skies on a regular basis. The solar calendar found in Arizona has a spiral shape. It was unclear of what the spiral shape is, but archaeologists deciphered it in 1990. The shadows revealed that the makers used it as a mechanism to track the equinoxes and solstices for ceremonies and other purposes. However, the ancients didn’t follow the summer solstice and archaeologists don’t know why.