Freeman Park Sinkholes EarthCache
Hidden : 2/10/2009
Difficulty:
1.5 out of 5
Terrain:
1.5 out of 5

Size: Size: not chosen (not chosen)

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Geocache Description:





Features of a Karst Landscape
A karst landscape has sinkholes, sinking streams, caves, and springs. Kentucky is one of the most famous karst areas of the world. Much of the state's beautiful scenery, particularly the horse farms of the Inner Bluegrass, results from the development of karst landscape. Karst underlies regions of major economic importance to the state. Many of Kentucky's cities, including Frankfort, Louisville, Lexington, Bowling Green, Elizabethtown, Munfordville, Hopkinsville, Russellville, Princeton, Lawrenceburg, Georgetown, Winchester, Paris, Somerset, Versailles, and Nicholasville, are partly or entirely underlain by karst.
Springs and wells in karst areas supply water to thousands of homes. Much of Kentucky's prime farmland is underlain by karst. A substantial portion of the Daniel Boone National Forest, with its important recreational and timber resources, is underlain by karst.
Caves also provide recreational opportunities and contain unique ecosystems. Mammoth Cave, with over 350 miles of passages, is the longest surveyed cave in the world. Two other caves in the state are over 30 miles long, and 10 Kentucky caves are among the 50 longest in the United States.
The term "karst" is derived from a Slavic word that means barren, stony ground. It is also the name of a region in modern Slovenia near the border with Italy that is well known for its sinkholes and springs. The name has been adopted by geologists as the term for all such terrain.
A karst landscape most commonly develops on limestone but can develop on several types of rocks, such as dolomite, gypsum, and salt. The karst terrains of Kentucky are mostly on limestone and formed over hundreds of thousands of years. As water moves underground, from hilltops toward a stream through tiny fractures in the limestone bedrock, the rock is slowly dissolved away by weak acids found naturally in rain and soil water.
Karst landscapes are commonly characterized by sinkholes, sinking streams, closed depressions, subterranean drainage, large springs and caves. Karst regions are susceptible to unique problems such as sinkhole collapse, sinkhole flooding and rapid groundwater pollution. Springs in karst areas are an important, productive source of groundwater. Rare biologic communities and endangered species can be found in the fragile underground environments developed in karst landscapes.



SINKHOLES DEFINED
Geologists classify sinkholes based on their geometry and how they developed. Understanding sinkhole dynamics is critical to detecting and mitigating damages these karst features can cause.
1. Collapse sinkholes occur when the bridging material over a subsurface cavern cannot support the overlying material. The cover collapses into the cavern and a large, funnel-shaped depression forms. Collapse sinkholes can vary in size from 1 or 2 feet deep and wide, to tens of feet deep and wide. Unlike large collapses, like those in Florida where the cover over the limestone is very thick, cover-collapse sinkholes in Kentucky are unlikely to swallow entire houses or businesses. Collapse sinkholes in Kentucky do severely damage buildings , drain farm ponds, damage roads, and wreck farming equipment. The thickness and cohesiveness of the soil cover determine the size of a cover-collapse sinkhole. In Kentucky the thickness of soil, sand or clay, and bedrock fragments over limestone bedrock is typically less than 25 feet, so cover-collapse sinkholes more than 20 feet in diameter are uncommon.
2. Solution sinkholes result from increased groundwater flow into higher porosity zones within the rock, typically through fractures or joints within the rock. An increase of slightly acidic surface water into the subsurface continues the slow dissolution of the rock matrix, resulting in slow subsidence as surface materials fill the voids.
3. Alluvial sinkholes are older sinkholes that have been partially filled with marine, wetland or soil sediments. These features are common in Florida, where the water table is shallow, and typically appear as shallow lakes, cypress “domes” and wetlands.
4. Raveling sinkholes form when a thick overburden of sediment over a deep cavern calves into the void and pipes upward toward the surface. As the overlying material or “plug” erodes into the cavern, the void migrates upward until the cover can no longer be supported and then subsidence begins.
Farming in karst areas must take into account the lack of surface water. The soils may be fertile enough, and rainfall may be adequate, but rainwater quickly moves through the crevices into the ground, sometimes leaving the surface soil parched between rains. Water supplies from wells in karst topography may be unsafe, as the water may have run unimpeded from a sinkhole in a cattle pasture, through a cave and to the well, bypassing the normal filtering that occurs in a porous aquifer. Karst formations are cavernous and therefore have high rates of permeability, resulting in reduced opportunity for contaminants to be filtered out.

To claim this earthcache as a find, please submit a photo of yourself with your GPSr at the given coordinate with the sink hole and the tree in the background.
And to demonstrate the educational value of your visit, please email me the answers to the following three questions:
1. What kind of sinkhole is at these co-ordinates?
2. How many sinkholes with trees growing in them can you see from this location?
3. Name 2 items that have been placed in the sinkholes in an attempt to protect livestock?
Thank you for visiting, and Happy Caching! Update! Progress has changed the terrain and the sinkholes. To qualify for this cache email me and tell me something about the general area where the sinkholes were as it is now.

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