Nashville Basin
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The Nashville Basin is a geographic term used to describe the area surrounding Nashville, Tennessee. The term would not be correct in the geologic sense, as geologically this structure is more properly known as the Nashville Dome, as the underlying rock strata all dip downwards away from Nashville. In fact, this area being a geological dome contributed to the formation of the area as a geographical basin. Uplifted strata (rock layers) in the center of a geological dome have higher potential erosive energy than the surrounding strata, due to their being physically higher. Erosion thus acts on the uplifted area at a greater rate than on the surrounding flat-lying area, creating a low area, i.e. a basin. This area is also sometimes referred to as the Central Basin of Tennessee.
It is apparently uphill in any direction out of Nashville, as a visit to any of the taller bulidings in the downtown area will readily make apparent. Nashville itself is located in the northwestern portion of this basin. Travelling north or west out of Nashville one will soon begin the climb up the escarpment that marks the bordering geographic/geologic province, the Highland Rim. The basin extends for approximately forty-five to sixty miles to the east of Nashville, and about eighty miles to the south, near the Tennessee-Alabama line.
The Nashville Basin is underlain primarily by limestone from the Ordovician Period. This area and a similar, but smaller area surrounding Lexington, Kentucky referred to as the "Kentucky Bluegrass" area, are the two primary areas of this sort in the world.
The Inner Basin of the flattest terrain and most limestone-derived soil chemistry is located to the south and east of Nashville, primarily in the counties of Maury, Rutherford, Coffee, and Bedford. Here also are seen the horse farms somewhat reminiscent of the Kentucky Bluegrass region. Supposedly the underlying rock weathers to a soil particularly suited to the growing of the sorts of grasses most favored by horses. Limestone glades (or cedar glades), open areas where the flat limestone rock is denuded of overlying soil or nearly so, provide an environment for flora [1][2] unlike any other in the world.
