Geology topics

M. W. Bradley

Publications and source records attributed to M. W. Bradley.

11 recordsLinked to original sources

USGS1987

Construction, geologic, and hydrologic data for observation wells in the Reelfoot Lake area, Tennessee and Kentucky

Twenty-three observation wells were installed at 12 sites in the Reelfoot Lake area of Kentucky and Tennessee during July 1986. The wells were installed to supplement an existing water level network and to provide additional data on the hydraulic characteristics and vertical hydraulic gradients in the alluvial aquifer near Reelfoot Lake. Well yields ranged from less than 20 gallons per minute to about 140 gallons per minute. The specific capacities of the wells ranged from less than 1 to 17.1 gallons per minute per foot of drawdown. Three stratigraphic sequences were encountered during drilling. Clay and silty clay was about 40 feet deep near the southwest corner of Reelfoot Lake. Predominantly medium- to coarse grained sand occurred below about 15 feet of silt and clay near the west and northwest sides of Reelfoot Lake. Along the western limit of the study area, near Lake No. 9 and the Mississippi River, about 20 to 30 feet of silt and silty sand occurred below land surface.

Kentucky, Tennessee↗

USGS1986

Preliminary delineation and description of the regional aquifers of Tennessee – The central basin aquifer system

The Central Basin aquifer system is composed of Devonian and Ordovician carbonate and shale rocks. This aquifer occurs west of the Valley and Ridge province and crops out in the Central Basin and the Sequatchie Valley of Tennessee. Ground water in the Central Basin aquifer occurs primarily in solution openings and fractures, and the flow system is generally limited to 300 feet or less below land surface. However, some fracture and minor faults may allow vertical recharge to the underlying Knox Group, which marks the lower boundary of the Central Basin aquifer system. Away from the Central Basin, the upper limit of the Central Basin aquifer system is the Chattanooga Shale, an effective confining unit. The Central Basin aquifer system, an important source of drinking water, supplies most of the rural domestic and many public supplies of drinking water in the Central Basin and the Sequatchie Valley. Dissolved-solids concentrations often are less than 500 milligrams per liter where the aquifer is part of a dynamic flow system. Dissolved-solids concentrations may reach thousands or tens of thousands of milligrams per liter below the zone of dynamic flow.

Tennessee↗

USGS1986

Preliminary delineation and description of the regional aquifers of Tennessee -- Highland Rim aquifer system

The Highland Rim aquifer system is primarily composed of Mississippian carbonates. This aquifer system occurs west of the Valley and Ridge province. It crops out in the Highland Rim and the Sequatchie Valley. It has been removed by erosion from the Central Basin. Ground water in the Highland Rim aquifer system occurs primarily in secondary openings. These openings include solution openings, joints, and faults. The Chattanooga Shale is the lower confining layer for the Highland Rim aquifer system. Under the Cumberland Plateau, this aquifer system is separated from the overlying Pennsylvanian formations by the Pennington Shale. The Highland Rim aquifer system is an important source of drinking water. It supplies most of the rural, domestic and many public supplies of drinking water in the Highland Rim. Where there is a dynamic flow system, dissolved-solids concentrations are less than 500 milligrams per liter. However, isolated cells may exist where the ground water has dissolved-solids concentrations of more than 1,000 milligrams per liter.

Tennessee↗

USGS1986

Preliminary delineation and description of the regional aquifers of Tennessee– Tertiary aquifer system

The Tertiary aquifer system in Tennessee is composed of sands and clays of Quaternary and Tertiary age. The aquifer system occurs in west Tennessee from the Mississippi River east to the outcrop of the Porters Creek Clay. Groundwater in the Tertiary aquifer system is recharged at outcrops and through overlying permeable deposits. The underlying Porters Creek Clay acts as the lower confining layer. The Tertiary aquifer system is the single most prolific source of groundwater in Tennessee. The water quality is excellent with generally less than 500 mg/L dissolved solids.

Tennessee↗

USGS1986

Preliminary delineation and description of the regional aquifers of Tennessee– The Cretaceous aquifer system of west-Tennessee

The Cretaceous aquifer system in western Tennessee is composed of sand, gravel, and clay. The aquifer system is under confined conditions except in the outcrop area. Ground water is recharged by precipitation on the outcrop area and through some overlying permeable deposits. The hydraulic gradient in the confined aquifers is about 1 foot per mile generally toward the west. The Cretaceous aquifer system unconformably overlies the consolidated Paleozoic formations and is overlain and confined by the Porters Creek Clay. The Cretaceous aquifer system is used as a source of water supply primarily in the outcrop area. West of the outcrop of this aquifer system, ground water can be obtained at shallower depths and with better water quality. The water of the Cretaceous aquifers generally have very good quality in the outcrop area. The dissolved solids increase down gradient to more than 1,000 milligrams per liter in parts of Shelby County. High iron concentrations are present in some areas.

Tennessee↗

USGS1986

Preliminary evaluation of the Highland Rim aquifer system in Tennessee for receiving injected wastes

The U.S. Environmental Protection Agency has authority under the Safe Drinking Water Act to protect underground sources of drinking water from contamination by deep well injection. An aquifer, however, may be exempted from protection and used for injected wastes where the aquifer meets criteria established in the Agency’s Underground Injection Control program. The Highland Rim aquifer system in Tennessee consists of Mississippian age carbonate rocks and occurs from the Valley and Ridge of East Tennessee to west of the Tennessee River. This aquifer contains potable water and is an important source of drinking water for municipal and domestic supplies on the Highland Rim. The Highland Rim aquifer system under parts of the Cumberland Plateau is not currently used as a source of drinking water and is not expected to be used in the future. These areas meet parts of the Environmental Protection Agency’s Underground Injection Control criteria for exempting aquifers to receive injected waste.

Tennessee↗

USGS1986

Preliminary evaluation of the basal sandstone in Tennessee for receiving injected wastes

The U.S. Environmental Protection Agency is authorized, under the Safe Drinking Water Act, to administer the Underground Injection Control program. This program allows for the regulation of deep-well disposal of wastes and establishes criteria to protect underground sources of drinking water from contamination. The basal sandstone in Tennessee occurs west of the Valley and Ridge province at depths of 5,000 to 9,000 feet below land surface. The basal sandstone consists of about 30 to 750 feet of Cambrian sandstone overlying the crystalline basement complex. The basal sandstone is overlain and confined by shale and carbonate rocks of the Middle and Upper Cambrian Conasauga Group. Hydrologic data for the basal sandstone, available from only three sites (four wells) in Tennessee, indicate that the basal sandstone generally has low porosity and permeability with a few zones having enough permeability to accept injected fluids. Limited water-quality data indicate the basal sandstone contains water with dissolved-solids concentrations exceeding 10,000 milligrams per liter. Since the dissolved-solids conce ntrations exceed 10,000 milligrams per liter, the basal sandstone is not classified as an underground source of drinking water according to U.S. Environmental Protection Agency regulations.

Tennessee↗

USGS1986

Preliminary evaluation of the Knox Group in Tennessee for receiving injected wastes

The U.S. Environmental Protection Agency is authorized under the Safe Drinking Water Act to protect underground sources of drinking water from contamination. However, an aquifer may be exempted from protection and used for injected wastes where the aquifer meets criteria established in the U.S. Environmental Protection Agency's Underground Injection Control program. The Knox Group in Middle and West Tennessee occurs primarily in the subsurface, and the top of the Knox Group ranges from about 350 to 3,000 feet below land surface. The upper part of the Knox Group (upper Knox aquifer) is an important source of drinking water in parts of the Central Basin and the Highland Rim provinces. The lower part of the Knox Group is currently being used for injected wastes at New Johnsonville on the western Highland Rim and at Mount Pleasant in the Central Basin.

Tennessee↗

USGS1985

Delineation and description of the regional aquifers of Tennessee — The Knox Aquifer in central and west Tennessee

The Knox aquifer is composed of the Cambrian and Ordovician age carbonate rocks of the Knox Group. This aquifer occurs throughout Tennessee, west of the Valley and Ridge province. The Knox crops out in the Sequatchie Valley and in the Wells Creeks cryptoexplosive structure on the Northwestern Highland Rim. Groundwater in the upper Knox occurs primarily in solution openings. The aquifer may be recharged through fractures and faults in the overlying Ordovician limestones in Middle Tennessee. The underlying Conasauga Shale acts as the lower confining layer. Throughout parts of the Central Basin province, the Knox aquifer is an important source of water for rural domestic supplies. In these areas, groundwater from the Knox generally has less than 1,000 milligrams/L dissolved solids. Away from the Central Basin, the dissolved solids concentrations increases. It may approach brine concentrations under the Cumberland Plateau.

Tennessee↗

USGS1985

Preliminary evaluation of the Central Basin aquifer system in Tennessee for receiving injected wastes

The U.S. Environmental Protection Agency is authorized to protect underground sources of drinking water from contamination. However, an aquifer may be used for injected wastes where the aquifer meets criteria established in the Environmental Protection Agency’s Underground Injection Control program. The Central Basin aquifer system in Tennessee consists of Ordovician to Devonian carbonate rocks and it occurs from the Valley and Ridge province to west of the Tennessee River. This aquifer system is currently used for drinking water in the Central Basin and western Highland Rim, but is not used for drinking water in the northern Highland Rim nor the Cumberland Plateau provinces.

Tennessee↗

USGS1984

Ground water in the Dickson area of the western Highland Rim of Tennessee

A hydrologic study of the Dickson, Tenn., area provided additional information on the occurrence of ground water in the Mississippian carbonate rocks of the western Highland Rim. Twenty-six wells were drilled to determine the occurrence of ground water in relation to topographic position, regolith thickness, streamflow gains or losses, lithology of the underlying formations, and linear features. Yields of 26 test wells ranged from 0 to about 300 gallons per minute and averaged about 68 gallons per minute. Nine wells yielded 80 to about 300 gallons per minute; specific capacities ranged from about 0.71 to 12.7 gallons per minute per foot of drawdown. Seven of these nine wells yielded water from solution openings in the Warsaw Limestone. The other two wells yielded water from gravel and sand in the regolith. Aquifer tests were conducted on two wells. One well was pumped at an average rate of 350 gallons per minute for 72 hours with 39.77 feet of drawdown. The second well was pumped for 8 hours at 120 gallons per minute with 20.86 feet of drawdown. The water from both wells was of generally good quality. Water from one well had a dissolved solids concentration of 170 milligrams per liter. The dissolved solids in the water from a second well was estimated from specific conductance as about 160 milligrams per liter. Thick regolith and the presence of fine-grained limestone interbedded with coarse-grained limestone near the base of the regolith appear to be significant conditions for the development of solution openings that yield large amounts of water. Seventy percent of the test wells in which these conditions occurred yielded 80 gallons per minute or more.

Tennessee↗