Sinkholes are a common feature of Florida's landscape. They are only one of many kinds of karts landforms, which include caves, disappearing streams, springs, and underground drainage systems, all of which occur in Florida. Karts is a generic term which refers to the characteristic terrain produced by erosion processes associated with the chemical weathering and dissolution of limestone or dolomite, the two most common carbonate rocks in Florida. Dissolution of carbonate rocks begins when they are exposed to acidic water. Most rainwater is slightly acidic and usually becomes more acidic as it moves through decaying plant debris.
Limestone's in Florida are porous, allowing the acidic water to percolate through their strata, dissolving some limestone and carrying it away in solution. Over eons of time, this persistent erosion process has created extensive underground voids and drainage systems in much of the carbonate rocks throughout the state. Collapse of overlying sediments into the underground cavities produces sinkholes.
 When groundwater discharges from an underground drainage system, it is a spring, such as Wakulla Springs, Silver Springs, or Rainbow Springs. Sinkholes can occur in the beds of streams, sometimes taking all of the stream's flow, creating a disappearing stream. Dry caves are parts of karst drainage systems that are above the water table, such as Marianna Caverns.
Suggested reading: Lane, Ed, 1986, Karst in Florida: Florida Geological Survey Special Publication 29, 100 p.
Many researchers have conducted in-depth studies of karst and related features. Many of the statements herein are general statements that have been drawn primarily from Beck and Sayed (1991) and Waltham (1989).
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 Sinkholes are only one part of the total landscape that is formed on rocks that are relatively easily dissolved. The solution process also creates unusually large pores and channels in the bedrock, including caves, through which ground water surges to the land surface as springs. In general the solution process begins as rainwater absorbs carbon dioxide from the atmosphere and as it percolates downward through the soil, which is high in CO2 generated during the decay of organic matter. This makes the recharge water weakly acidic (carbonic acid), and it is this acid that dissolves the limestone (CaCO3).
This is a powerful process, an estimate of 600 tons per day of CaCO3 is dissolved in the water being discharged from Silver Springs in Ocala, Florida (Sellards, 1910). A summary of limestone dissolution rates from sites worldwide range from 55 to 100 m3 km-2 a-1 with majority of dissolution occurring in the upper 10 meters or in subsurface conduits (Ford and Williams, 1989).
When the slightly acidic water reaches the limestone it continues moving downward through any interconnected pores or fractures, under the force of gravity. As the weak carbonic acid flows downward through the limestone, it dissolves and enlarges any pores or cracks through which it flows. The most favored vertical path dissolves more rapidly than the surrounding areas, because it carries more water. Because it is now larger it can transmit more water in ever greater quantities, thus pirating drainage from the surrounding rock mass. This "self accelerating" process results in few greatly enlarged tubes or pipes permeating down through the limestone, with little dissolved rock in between. The weight of the over lying soils above these areas have a tendency to cave in over time thus producing a sinkhole. The USGS links listed below can further explain the sinkhole processes.
Check out:
Karst information @ http://coastal.er.usgs.gov/ and http://www.usgs.gov
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