I grew up in rural, mountainous east Tennessee, and coal mining was one of the key industries in that region. I remember very well climbing all over a coal tipple that was at least 100 feet high. Coal tipples were used to dump coal down an inclined steel ramp with various spaces between the steel rods.... it was a cheap and gravity based way to sort different sizes of coal. My friends and I climbed all over that thing when no one was around, and it could have easily killed us if we'd fallen. Ah, good times.