I was skating on a small lake north of here and noticed a cool pattern in the cracks in the "black" (transparent) ice: everytime the crack bends to the left there would be one kind of pattern, and everytime the same crack bent to the right there would be the opposite: en-echelon (means discontinuous) up shallow merging with a continuous crack at depth: like a series of petals, about the sized and shape of potato chips. I noticed this now after all these years of skating because we see the same patterns on real faults (en-echelon), and with strike-slip fauls these can merge with depth (called flower structures). I did not have my camera, and did not go back the next day-now it has snowed and I have to wait a year or more to study this pattern in more detail. About 22 years ago I was skating on thicker black ice and an ice fisherman hit an axe into the ice a quarter mile away. A crack propagated right by me, hissing as it went.-Chris