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Artesian water in Tertiary limestone in the southeastern States

1966; United States Government Publishing Office; Linguagem: Inglês

10.3133/pp517

2330-7102

V. T. Stringfield,

Water Quality and Resources Studies

In Florida, southern Georgia, and adjacent parts of Alabama and South Carolina an artesian aquifer system of Tertiary age is the source of some of the largest groundwater supplies in the United States.The aquifer system consists of as many as eight formations, chiefly limestone.The area of this system discussed in this report includes all Florida and most of the Coastal Plain in Georgia as well as adjacent parts of South Carolina and Alabama and extends from the Atlantic coast as far inland as the Fall Line in a few places.The area is in the Atlantic and Gulf Coastal Plain province-a region of plains and low hills.Most of the region is covered by Pleistocene coastal terraces rising from sea level to as much as 270 feet above sea level; the higher hills between the terraces and thf;' Fall Line are as much as 600 feet above sea level.Valleys are cut as much as 100 feet below some uplands.Some of the principal streams, such as the Savannah River, rise in the Piedmont province and flow across the Coastal Plain in Georgia and adJacent parts of South Carolina, Florida, and Alabama to the sea.The other streams rise within the area of the report.The climate ranges from temperate in South Carolina and Georgia to subtropical in southern Florida.The average annual rainfall ranges from about 38 to 60 inches.The lowest rainfall is on the Florida Keys.Sedimentary formations which crop out in this region range from Cretaceous to Recent in age.Igneous and metamorphic rocks underlie the Cretaceous formations and appear at the surface in the Piedmont province.The Cretaceous formations consist chiefly of sand, gravel, and clay in the areas where they are at or near the surface.The overlying Tertiary formations consist chiefly of limestone, dolomite, and marl, with some anhydrite and gypsum.Some formations grade into sands and other clastic material in western Florida, southeastern Alabama, the southwestern part of the Coastal Plain in Georgia, the northeastern part of the Coastal Plain in Georgia, and adjacent parts of South Carolina.Pleistocene and Recent deposits, consisting chiefly of sand and gravel, clay and shells, generally are less than 100 feet thick.In southeastern Florida the Pleistocene formations, however, include at least 250 feet of limestone, marl, sand, and shell beds.The Tertiary formations are at or near the surface in belts approximately parallel to the Cretaceous outcrops and the Fall Line in Georgia and adjacent parts of Alabama and South Carolina.The Tertiary formations are also near the surface on some geologic structural features, such as the Ocala uplift in north-central Florida and on the Chattahoochee anticline in western Florida.Except where affected by local structural features, the formations dip gently toward the coast at right angles to the belt of outcrops.The formations dip in all directions from the Ocala uplift.In Florida,