The Science Behind Sinkholes: How and Why Sinkholes are Formed

Many Florida residents (myself included) have a secret fear of sinkholes.  The earth suddenly opens up before your feet, and decides that it is hungry for your house, your car, and your very being.  Terrifying to think about, and highly unlikely to actually occur.  That being said, sinkholes tend to occur in areas that have “karst” topography.  What this means, is that the underground landscape is porous (filled with holes), a bit like a sponge or swiss cheese.    The majority of Florida, being composed primarily of limestone, most definitely qualifies as a karst region, so its no surprise that Florida has some noteable sinkholes.  Most sinkholes in Florida are formed by one of two different processes. 

The first process occurs when there has been a great deal of rain.  The rain filters down into the ground, and wears away at the limestone beneath the ground.  Gradually a hole begins to form underground, and these holes will stay intact until the rock is no longer able to support it’s own weight.  When that happens, the underground cavern collapses, and a sinkhole is formed on the surface. 

The second way that a sinkhole forms is when there has been a drop in the water table.  For example, during severe droughts, more water is drawn out from the aquifer than goes in.  This leads to a drop in the water level, and some of the caverns in the aquifer collapse, as they are no longer able to support their own weight.

Several noteable sinkholes can be found right here in North Florida.  The Devil’s Millhopper is located just outside of Gainesville and makes a great day trip.  The Devil’s Hole is located just outside of Starke, and has a great rope swing to help visitors take the plunge into the chilly 72° water.  Also just outside of starke is Kingsley lake.  A great place to go boating, water skiing, and fishing.

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