Karst topography is a geological formation shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rock such as limestone or dolomite.. Karst landscape, which occurs in many parts of Eastern Tennessee, has springs, sinking streams, caves, and sinkholes. The karst terrains of Tennessee 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.
A sinkhole, also a sink, snake hole, swallow hole, swallet, doline, or cenote, is a natural depression or hole in the Earth's surface caused by karst processes, such as the removal of soil or bedrock, sometimes both, by water. They may be formed gradually or suddenly, can be any size and depth, and are found worldwide. Simply stated: Sinkholes are the result of water movement through limestone rock formations. As water goes through the natural cracks in these formations, the limestone is slowly dissolved, leaving open spaces in the rock structure. When enough limestone has dissolved to weaken the rock, the surface soil collapses into a cone shaped depression commonly called a sinkhole. The size of the sinkhole is dependent on several factors including groundwater level, surface water infiltration rate, overburden depth, and water chemistry (acidity). Once formed, a sinkhole can grow in size unpredictably, based on conditions specific to that area.
Clarksville TN sits in one of the most interesting areas of karst topography in the world. It is part of a region known to geologists as the Western Highland Rim Plain. This region includes northern middle Tennessee and extends into Eastern Kentucky where it is called the Pennyroyal Plain and Mammoth Cave Plateau. The only region in the world with more karst features is Slovenia in southern Europe.
This earthcache will bring you to one of several sinkholes in Clarksville. To demonstate the educational value of this cache, please answer the following questions. Submit the answers to these questions to the following email: email@example.com Do not post your answers with your log. Anyone who logs the cache without answering the questions within 24 hours of logging will have their logs deleted. Photos are optional, but appreciated and encouraged.
There is a chain link fence surrounding the sinkhole. You should never go past the fence to view this feature.
1. What is the geological name of the region that Clarksville, TN is in?
2. In your own words, what causes a sinkhole?
3. What causes the acidity in the water?
4. While visiting the site estimate the dimensions of the sinkhole.
5. Is there any evidence that the sinkhole is getting bigger?