Glass after a fire
It goes without saying that fires are hot, but they are not all the same level of heat. Your average campfire is nothing compared to the temperature that a house fire can burn at once it really gets going. This picture shows us what can happen in the aftermath of such a fire.
Glass melts at 2522* to 2912* Fahrenheit. The glass in this picture, just as it was beginning to melt then solidified instantly as it was cooled down by surrounding air. I can’t imagine the heat necessary to do this, or the devastation that it would have left in its wake.