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February 16, 2006

Devil's Millhopper Geological State Park

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Hi Everyone!! Another great day at an awesome State Park!

Devil’s Millhopper gets its unique name from its funnel-like shape. During the 1800’s farmers used to grind grain in gristmills. On the top of the mill was a funnel-shaped container caller 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 what fed bodies to the devil. Hence, Devil’s Millhopper.

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View from the top... Can't see it? We'll get closer...

Limestone is the foundation on which the surface of Florida sits. Although this stone is very hard, it is easily dissolved by a weak acid. Rainwater becomes a weak carbonic acid from contact with carbon dioxide in the air. As it soaks into the ground, passing through dead plant material on the surface, it becomes even stronger. When this water reaches the limestone layer, small cavities are formed as the rock slowly dissolves away. This process continues over a very long time until a large cavern is formed. 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.
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Slopes of this sink provide a cut-away view of central Florida’s geologic past. Each layer of sediment contains a record of events and animals that lived before. Marine animal shells in the lower layers indicate that this area of Florida was once covered by the sea. Bones and teeth of land animals found in more “recent??? layers indicate that the sea has receded.

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The sinkhole is 120 feet deep and 500 feet across. The depth of the ravine, the presence of certain plants and animals unique to this area, and archaeological clues suggest the sinkhole is quite old. The upper half or so may have been formed about ten to fifteen thousand years ago. The lower, more vertical portion does not appear to be more than one thousand years old, thus indicating the Devil’s Millhopper was formed in at least two stages.

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The sight and sound of water flowing down the slopes of the sink provide one of the most enjoyable features of the park. Beginning as rain, the water seeps down through the ferns and dense vegetation and drains through the soil into a layer of limestone. Clay beneath the stone prevents further downward movement of the water but then forces it to flow along the limestone layer. This phenomenon is called a perched water table. It then spills out to form the springs that surround the sink. There are about 12 springs her. Some cascade down to the bottom where they flow along and into a natural “drain??? so that the water eventually finds its way to the Gulf of Mexico.

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Millions of years ago this area was home to a variety of animals that have since become extinct. Only a few still exist as they did then. Replaced by minerals in the earth, their bones and teeth become fozzilized. Sinkholes and ravines cause their skeletons to break apart. Moving water erodes upper layers of sediment and exposes these remains. As each fragment is unearthed it is carried along by the water. As water slows, it deposits a conglomerate of diaassembled bones and teeth.
The fossils in this display were found in creeks and ravines at the Devil’s Millhopper and San Felasco Hammock. The animals they came from lived five and ten million years ago.

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1. Tooth- sperm whale (Physeteridae)
2. Rib- dugong (Metaxytheriam floridanum)
3. Tooth- great white shark (Carcharodon megalondon)
4. Tooth- juvenile dolphin (Dolphinus delphis)
5. Cannon bone (Metacarpal)- camel (camelidae)
6. Teeth- Crocodile or Gavial
7. Tooth- tiger shark (Galeocerdo aduncas)
8. Teeth- horse (Pseudhipparion skinneri)
9. Tooth- horse (Cormohipparion ingenum)
10. Shell fragment- Tortoise (Geochelone)
11. Dorsal arch bone- Fish
12. Inner ear bone- whale
13. Tooth- Mako Shark (Isurus)
14. Foot bone (Metapodial)- camel (Camelidae)
15. Shell fragment- tortoise (Geochelone)
16. Mouth plate- Stingray
17. Snout Fragment- Dugong (Metaxyheriam

Posted by Heather at February 16, 2006 08:19 PM


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