Sunken Ice
I was walking in the Cotswolds over the last couple of days and along the route I noticed an interesting phenomenon. There was a puddle of water which had some ice in it, since the temperature was pretty chilly, but what was unusual was that the ice was at the bottom of the puddle.
Ice normally floats so it tends to be on top of the water but in this case the ice must have frozen into some cracks in the ground which would have kept it locked in place. Then when some more water flowed over the top of it the ice couldn’t float up the the surface because it was stuck.
Unfortunately I did not have a camera with me at the time, otherwise I would have taken a photo of it. I haven’t noticed the effect at any other time. There was about 5cm of water above the ice.