Melted concrete II
A few years ago during a major storm a main power cable was torn off the poles and smacked into the sidewalk down the street from us. There was enough juice that the concrete melted and bubbled up in crazy patterns. Some of the bubbles appeared very much like glass (maybe they were glass). Fortunately, no one was injured.
As soon as I saw the "melted" theme I thought of these marks, which fascinate me for some reason.
These days the big bubbles and black surface marks have worn away but the odd-shaped divots remain as a reminder that those power lines are hot hot hot.