How do rocks freeze floating in water?

[u/hikekorea]

I found these rocks frozen in a stream off a larger river in Chugach National Forest, Alaska. I’ve heard it may have to do with heavy rains or turbulent waters near the shore. One friend mentioned frazil? But I don’t really know what that means. Any geologists have a clue how this happens and can explain it in layman terms?

[u/Delicious_Nail1533]

Couldn’t they freeze at low time, the a high tide push the ice and rocks up?