Floating pancakes (my term) or lily pads (Mary's term) of ice.
DP052-2014 Posted February 21; processed Feb. 20
I've been puzzling over this ice formation ever since I saw it. I now think I have a possible explanation for how it formed. It is on a stretch of the river immediately downstream from the tailraces of Geddes Dam. Water comes out at the bases of the metal plates of the dam gates under high pressure. The resulting turbulence creates a lot of foam. That soon disperses into rafts of bubbles that float downstream, and typically form into circular disc shapes. I believe that the round plates of ice are nothing more exotic than frozen groups of bubbles. In support of this hypothesis I note that the top surfaces of the plates are bumpy, as they would be if formed from bubbles (not flat, as they'd be if formed from fractured sheets of ice), and that you can see bubbles or remnants of bubbles around the edges of some of the plates. Voilà! Pancake ice!
Taken February 12, 2014
(Title: Frozen Foam?)
Thanks so much for all the kind comments on my photo of the duck floating on a reflection, accompanied by some of this pancake ice. I was a bit under the weather, and didn't spend much time on the computer. I hope to catch up today.