Groundwork was laid in the stars By SETH MULLER

Near the Crack-in-the-Rock pueblo in Flagstaff’s Wupatki National Monument, a formation known as Calendar Wall has a portal. When the sun is halfway between the equinox and the solstice in November and February, the sun appears at the portal’s center. …

[A] ruin [in Chaco Canyon] known as the Great House of Wijiji has an alignment with a notch in front of the eastern horizon. Two weeks before the winter solstice the sun rises at the north corner of the notch, and two weeks later it’s at the south end of the notch.

Researchers believe a ”sunwatcher” would gather important information from such markers in order to determine preparation times for ceremonial events or agricultural activities. Wijiji is one of many structures at Chaco that has formations demarcating the seasons.