Just a few days ago I walked south from Afton accessing the river at Steamboat Park. The ice here is very dynamic with water flowing into the St Croix from small creeks and of course under the ice all the time. It’s a good idea to stay near the shore and DRY land.
Cracks get filled in from water flowing up from under the ice and refreezing in layers creating a banding effect almost like an agate.
Crystals form at open water areas (see misting background) and float in the air before landing on the frozen ice…like scattered chicken feathers.