Location: Devil’s Millhopper State Geological Park, Gainesville, FL
Found this bit of history about Devil’s Millhopper on the park website.
Devil’s Millhopper gets its unique name from its funnel-like shape. During the 1880’s, farmers used to grind grain in gristmills. On the top of the mill was a funnel-shaped container called a “hopper” that held the grain as it was fed into the grinder. Because fossilized bones and teeth from early life forms have been found at the bottom of the sink, legend has it that the millhopper was used to feed bodies to the devil. Hence, Devil’s Millhopper.
Florida sits upon a foundation of limestone rock. Although this stone is very hard, it can be easily dissolved by weak acid. Rainwater becomes a weak carbonic acid thru contact with carbon dioxide in the air. As it soaks into the ground, passing through the dead plant material on the surface, the acid becomes even stronger. When this acidic water reaches the limestone layer, small cavities form as the rock is slowly dissolved away. A large cavern is formed as this process continues over a long period of time. Eventually the ceiling of the cavern becomes so thin that it cannot support the weight of the earth above it. When the ceiling collapses, a sink is formed.
The sinkhole is 120 feet deep and 500 feet across. A one-half mile nature trail follows the rim, and there is a 236-step stairway to the bottom of the sink. The state purchased this site in 1974, and the stairs were completed in 1976. Until that time, access in the area was limited.