Possible Clues:

• A turning point in June and December for ground soils, etc.
• Fish holding short stick in biannual event
• Fish, holding shortened rod in biannual event
• Seasonal turning point
• An occasion when the sun is furthest from the equator
• First day of summer or winter
• Season opener
• June/December event
• Lost cities heartlessly demolished, a turning point
• When the sun is farthest from the celestial equator