Model Spring EarthCache

Model (Great Western) Spring is located on Land Between the Lakes' "The Trace" or TN Hwy 49,  12 miles (15 minutes) south of the Golden Pond Visitor Center, 1 mile south of the Home Place Interpretive Center,  and 14 miles (20 minutes) north of Dover, TN. It is located just north of the ruins of the Great Western Furnace where parking is available.

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Geology of Land Between the Lakes' Stewart County:

You are standing in the The Western Highland Rim ecoregion of Tennessee. It is characterized by dissected, rolling terrain of open hills, with elevations of 400-1000 feet. The geologic base of Mississippian-age limestone, chert, and shale is covered by soils that tend to be cherty and acidic with low to moderate fertility.  Streams are relatively clear with a moderate gradient. Substrates are coarse chert, gravel and sand with areas of bedrock.   Unlike the Western Pennyroyal Karst of Kentucky and the Eastern Highland Rim of Tennesee and Kentucky, the region is lacking the small sinkholes and depressions that result from karst topography.

Natural Springs of Land Between the Lakes:

Limestone springs, such as Model Spring, are located throughout LBL.  These springs occur at the base of many limestone formations where they crop out on escarpments and hillsides.  This aquifer system is composed of Ft. Payne limestone of the Lower Missippian Period. 

Ground water is recharged from precipitation occurring over the outcrop area.  Water moves downhill through soil or cracks in this layer of bedrock until it is confined by an impervious layer of Maury Shale. Water is then forced out of the ground by natural pressure. The amount, or yield, of available water from springs may vary with the time of year and rainfall. Groundwater in the Highland Rim aquifer system is within 300 feet of land surface.  Water obtained from springs is similar to water pumped from shallow wells.

Dependent upon the constancy of the water source, a spring may be ephemeral (intermittent) or perennial (continuous). When water issues from the ground it may form into a pool or flow downhill, in surface streams. Most of the limestone springs in Stewart County flow year around and are used as drinking-water sources.

Minerals become dissolved in the water as it moves through the underground rocks. This gives the water flavor and even carbon dioxidebubbles, depending upon the nature of the geologythrough which it passes. Springs that contain significant amounts of minerals are sometimes called 'mineral springs'. Springs that contain large amounts of dissolved sodiumsalts, mostly sodium carbonate, are called 'soda springs'.

Model Spring:  Spring or Seep? Artesian or Gravity? Cool or Thermal?

Water which emerges at the surface naturally with a distinct current is called a spring. When a distinct current is not present, the flow is called a seep. Most springs and seeps represent water from rain or snow on some nearby higher ground which moves underground to where it comes up out of the ground. In some springs, the water bubbles up with a measurable force, indicating that it is under pressure, these are called artesian springs. Any spring having a temperature higher than the yearly average temperature for a given region is termed a thermal spring. This indicates a source of heat other than that of the surface climate, of which magmatic heat is an example. Based upon the pressure of the emergent water, any spring or seep which is not artesian may be classified as the gravity type. Gravity springs and seeps are those in which subsurface water flows by gravity from a high point of intake to a lower point of issue.

The amount of water that flows from springs depends on many factors, including the size of the crevices or caverns within the rocks, the water pressure in the aquifer, the size of the spring basin, and the amount of rainfall. If the groundwater is under sufficient pressure, the spring (or a well) might shoot water into the air-artesian well or spring. Human activities also can influence the volume of water that discharges from a spring—groundwater withdrawals in an area can reduce the amount of water and the pressure in an aquifer, causing water levels in the aquifer system to drop and ultimately decreasing the flow from the spring.