Minecraft wiki entry for Ice, associated text: Naturally generated ice on a frozen ocean.
Another view of naturally generating at a frozen ocean.
Naturally generated ice on a deep-frozen ocean.
Chunk borders as seen in a patch of ice.
The effect of a torch on ice exposed to the sky. Note that some blocks are at a light level that lets them alternately melt and freeze.
The melting pattern of a torch to ice.
The melting pattern of lava to ice.
Ice melting because of the nearby torch animation.