Geology topics
William Scott Parks
Publications and source records attributed to William Scott Parks.
Geology and ground-water resources of the Memphis Sand in western Tennessee
The Memphis Sand of the Claiborne Group of Tertiary age underlies approximately 7,400 square miles in western Tennessee. The formation primarily consists of a thick body of very fine to very coarse sand that includes subordinate lenses or beds of clay and silt at various horizons. The Memphis Sand ranges from 0 to about 900 feet in thickness, but where the original thickness is preserved, it is about 400 to 900 feet thick. The Memphis Sand yields water to wells in most of the area of occurrence in western Tennessee and, where saturated, makes up the Memphis aquifer. Recharge to the Memphis aquifer is from precipitation on the outcrop, which is a broad belt across western Tennessee, or by downward infiltration of water from the overlying fluvial deposits of Tertiary(?) and Quatemary age and alluvium of Quatemary age. Long-term data from five observation wells indicate that water levels have declined at average rates ranging from less than 0.1 to 1.3 feet per year during the period 1928-83. The largest declines have been in the Memphis area. Water from the Memphis aquifer generally is a calcium bicarbonate type, but locally is a sodium bicarbonate or mixed type. The water contains low concentrations of most major constituents and generally is suitable for most uses. Dissolved-solids concentrations range from 19 to 333 milligrams per liter. The results from 76 aquifer tests made in the Memphis area and western Tennessee during the period 1949-62 indicate that transmissivities range from 2,700 to 53,500 feet squared per day, and storage coefficients range from 0.0001 to 0.003. The Memphis aquifer provides moderate to large quantities of water for many public and industrial water supplies in western Tennessee and small quantities to numerous domestic and farm wells. Withdrawals for public and industrial supplies in 1983 averaged about 227 million gallons per day, of which 183 million gallons per day were in the Memphis area. The Memphis aquifer has much potential for future use, particularly at places outside the Memphis area.
Chemical character of ground water in the shallow water-table aquifer at selected localities in the Memphis area, Tennessee
The City of Memphis depends solely on ground water for its water supply. About 97 percent of inventoried pumpage in the Memphis area, which totaled about 194 Mgal/d in 1979, is from the Memphis Sand. This aquifer generally has been believed to be separated from the shallow water-table aquifer (alluvium and fluvial deposits) by a relatively thick and wide-spread confining bed consisting chiefly of clay. Studies by the Geological Survey in recent decades, however, have indicated that part of the recharge to the Memphis Sand probably is derived by vertical leakage from the shallow water-table aquifer through the confining bed and that locally "windows" of sand exist in the confining bed through which any contaminants in the shallow water-table aquifer could enter the Memphis Sand (See Criner and others, 1964, p. 30; Bell and Nyman, 1968, p. 7-8; Parks and Lounsbury, 1976, p. 26-27). More recently, additional evidence of vertical leakage being a component of recharge to the Memphis Sand was provided during the calibration of a digital computer model of the aquifers in the Memphis area. For this calibration a leakage factor, averaging about 20 percent over the Memphis area, had to be applied to the model in order to simulate known historic water levels in the Memphis Sand (J. V. Brahana, 1980, oral commun. ). This discovery has heightened concern about the possibility of contaminants being in the shallow water table aquifer, and thus, the potentiality for any contaminants to enter the Memphis Sand. Areas where the shallow water-table aquifer is most susceptible to contamination are those that have been or are being used for waste disposal. Historically, Memphis and Shelby County along with private concerns and industries have used dumps and landfills in two geologically and topographically different areas -- the flood plains of nearby streams and abandoned gravel pits in upland areas. These dumps and landfills have received a large variety of wastes including ashes, construction and demolition materials, garbage, rubbish, street refuse, and chemical and industrial wastes. Most of these dumps and landfills were closed in the early 1970's at the beginning of state regulation of waste disposal practices. Nevertheless, leachates from these waste disposal facilities presumably have been and are entering the shallow water-table aquifer.
Appraisal of Hydrologic Information Needed in Anticipation of Lignite Mining in Lauderdale County, Tennessee
Lignite in western Tennessee occurs as lenses or beds at various stratigraphic horizons in the Coastal Plain sediments of Late Cretaceous and Tertiary age. The occurrence of this lignite has been known for many decades, but not until the energy crisis was it considered an important energy resource. In recent years, several energy companies have conducted extensive exploration programs in western Tennessee, and tremendous reserves of lignite have been found. From available information, Lauderdale County was selected as one of the counties where strip-mining of lignite will most likely occur. Lignite in this county occurs in the Jackson and Cockfield Formations, undivided, of Tertiary age. The hydrology of the county is known only from regional studies and the collection of some site-specific data. Therefore, in anticipation of the future mining of lignite, a plan is needed for obtaining hydrologic and geologic information to adequately define the hydrologic system before mining begins and to monitor the effects of strip-mining once it is begun. For this planning effort, available hydrologic, geologic, land use, and associated data were located and compiled; a summary description of the surface and shallow subsurface hydrologic system was prepared: the need for additional baseline hydrologic information was outlined; and plans to monitor the effects of strip-mining were proposed. This planning approach, although limited to a county area, has transferability to other Coastal Plain areas under consideration for strip-mining of lignite.
Geologic map of the NE Memphis quadrangle, Tennessee
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Geologic map of the Tennessee portion of the NW Memphis quadrangle, Tennessee
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Geologic map of the Teague Quadrangle, Tennessee
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Summary of some current and possible future environmental problems related to geology and hydrology at Memphis, Tennessee
Memphis, Tennessee, like many other cities in the Nation, has some problems related to local geology and hydrology. The city is in the Coastal Plain physiographic province and is underlain at shallow depths by sand, clay, silt, gravel, and lignite. These post-Midway strata (Wilcox and younger) make up geologic units belonging to the uppermost Paleocene, Eocene, and Pliocene (?) Series of the Tertiary System and to the Pleistocene and Holocene Series of the Quaternary System. Environmental problems of immediate or future concern are associated with six general topics: (1) aggregate resources, (2) foundation materials, (3) earthquake hazards, (4) flood hazards, (5) water resources, and (6) solid waste disposal. Consideration of these topics in one report should provide an overall insight into the close interrelation of the problems and the need for coordinated studies of the geology and hydrology at Memphis.
Historic water-level changes and pumpage from the principal aquifers of the Memphis area, Tennessee: 1886-1975
The Memphis Sand ("500-foot" sand) supplies about 95 percent of the water used in the Memphis area for municipal and industrial purposes. In general, pumpage has increased at an irregular rate since the completion of the first well to this aquifer in 1886. These withdrawals are responsible for an almost continuous decline of water levels in wells throughout the Memphis area. Water-level data indicate that over the years a broad, regional cone of depression has developed in the potentiometric surface of the Memphis Sand and is centered near downtown Memphis. Areally smaller, subsidiary cones are superimposed upon this regional cone in areas heavily pumped by municipal and industrial wells. Pumpage from the Memphis Sand in Shelby County, Tenn., was 188 Mgal/d (million gallons per day) or 712 Ml/d (million litres per day) in 1975, although a maximum of 190 Mgal/d (719 Ml/d) was reached in 1974. Pumpage from the Fort Pillow Sand ("1,400-foot" sand) began in 1924 and increased at a yearly rate of about 0.6 Mgal/d (2.3 Ml/d) until 1942. From 1943 to 1962, pumpage averaged about 11.5 Mgal/d (43.5 Ml/d), then was reduced as MLGW (Memphis Light, Gas and Water Division) discontinued wells that became unserviceable. MLGW ceased pumping from the aquifer in 1974, and pumpage from the remaining industrial wells in Shelby County in 1975 was 4.4 Mgal/d (16.6 Ml/d). Water levels in the Fort Pillow Sand generally have risen since 1963. Water l evels in the aquifers in the Memphis area fluctuate inversely with changes in pumping. Analysis of observation-well and pumpage data indicates that local water levels can be altered by changing the pumping rates or by varying the areal distribution of pumping.
Geologic map of the Germantown Quadrangle, Tennessee
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