Preliminary Conceptual Models of the Occurrence, Fate, and Transport of Chlorinated Solvents in Karst Regions of Tennessee

Region name

Physiography

Aquifer characteristics

Typical lithologic units

Inner Central Basin

High sinkhole density; thin soil cover; low relief and few hills.

Relatively pure limestone,
<30 meters thick, separated by shaley limestones; minor confinement throughout.

Carters Limestone, Lebanon Limestone, Ridley Limestone, Pierce Limestone, Murfreesboro Limestone; Knox Group (paleokarst).

Outer Central Basin

Moderate sinkhole density and fluvial drainage, variable soil thickness; numerous hills (knobs).

Relatively pure limestones,
<30 meters thick, overlain and underlain by shaley limestone; major confinement at base (Hermitage Formation).

Leipers and Catheys Formations, Bigby and Cannon Limestones, Hermitage Formation.

Highland Rim

Sinkholes and caves well developed in upper units, decreasing down section; thick soils; relief extremely variable--well dissected over much of Western and parts of Eastern Highland Rim but nearly flat elsewhere on the Eastern Highland Rim and Pennyroyal Plateau.

Upper units thick, relatively pure limestone with many large openings, lower units increasingly impure limestones grading to chert and shale with relatively weak dissolution porosity; major confinement at base (Chattanooga Shale; locally Fort Payne Formation).

Ste. Genevieve Limestone (Pennyroyal Plateau), Monteagle Limestone (Eastern Highland Rim), St. Louis Limestone, Warsaw Limestone, Fort Payne Formation; Chattanooga Shale.

Coves and escarpments of the Cumberland Plateau

Sandstone caprock over cavernous limestone; steep-sided coves and escarpments; thick, coarse-grained colluvium at base of slopes.

Relatively thick, pure limestones interbedded with minor shale, sandstone, and chert, large springs and cave streams; minor confinement throughout.

Bangor Limestone, Hartselle Sandstone, Monteagle Limestone, St. Louis Limestone, Knox Dolomite in Sequatchie Valley east of Sequatchie Fault.

Valley and Ridge

Parallel, structurally controlled valleys and intervening ridges; significant cavern development.

Dolomites and dolomitic limestones of varying thickness, porosity, and composition; many large springs; major confinement at several stratigraphic horizons (Pumpkin Valley Shale, Nolichucky Shale, Athens Shale, Ottosee Shale, Bays Formation, and Martinsburg Shale).

Conasauga Group, Knox Group, Chickamauga Group, Jonesboro Limestone, Newman Limestone.

Western toe of the Blue Ridge

Coalesced alluvial and colluvial fans over carbonate rocks.

Fractured, cavernous carbonates between overlying alluvial/colluvial deposits and low-permeability, underlying shale and quartzites; large springs; major confinement at base (Chilhowee Group).

Shady Dolomite, Honaker Dolomite.