Re: [math-fun] why does the amazon river from space look like blood vessels?

Gary Antonick:

The Hans Havermann link is perfect: the ice is is slowly melting rather than shattering.

I took that photo of a shallow pond on 23 November 2008 in Toronto's High Park. The water was freezing rather than melting and there might have been an upwelling of current (I conjecture) at the hubs of of those radiating spokes.