Redditor odstane posted photos of a frozen pond, where the freeze pattern around rocks make the whole thing look like a topographical map. Or a rock garden. Either way, it's a bit of a stunning mystery.
In the comments to the original post, people have been guessing as to what caused this phenomenon. Rentalov, running with what it looks like, wrote:
My guess is the different depths of water in the pond caused it to freeze in increments, the deeper the water the slower the freeze. But I am in no way an expert on this.
Hagenar dismissed a guess of thermal stratification and turnover and offered this option:
Thermal stratification and turn-over are seen in large bodies of water, lakes and seas. A pond like this one is far too shallow to experience such phenomena.
The water was warmer than the air as the ice began to form. As the temperature fluctuated, the water lost more and more energy to the colder air. Ice began forming around cold objects and areas of the pond where the surface water was less prone to convective currents. With each successive temperature dip, more ice formed on the edges of that which had already frozen. That's how the pattern was created.
And teamwork between two people produced this guess, which has similarities to Hagenar's:
IICooKiiEII: I'm studying materials science and my guess would be that the ice particles would nucleate at the surfaces of the rock and continue from there, and this happened several times as temperatures could have fluxed and caused the freezing to stop. So the freezing basically started and stopped several times starting from the rock and then continuing from where the ice stopped, except when it continues where the ice had stopped, the new ice doesn't have the same crystal structure or is oriented differently, causing a mismatch in the ice
zcwright: I think you are on the right track. I would guess that a ring froze and then debris got stuck against the already frozen section. The freezing of the next ring would have a different crystal structure or lots of nucleation sites (and thus light scattering grain boundaries) that would cause the interface to be opaque.
Below are more photos of the pond as you evaluate the reasons given for them. Or, you can just not care about how and appreciate how pretty they are. That's a perfectly valid choice, too.