This information will help support the development and evaluation of management, regulatory, and monitoring decisions by other Federal, State, and local agencies to protect, use, and enhance water resources. The goals of the NAWQA Program are being achieved through ongoing and proposed investigations of 60 of the Nation's most important river basins and aquifer systems, which are referred to as study units. These study units are distributed throughout the Nation and cover a diversity of hydrogeologic settings. More than two-thirds of the Nation's freshwater use occurs within the 60 study units and more than two-thirds of the people served by public water-supply systems live within their boundaries. National synthesis of data analysis, based on aggregation of comparable information obtained from the study units, is a major component of the program. This effort focuses on selected water-quality topics using nationally consistent information. Comparative studies will explain differences and similarities in observed water-quality conditions among study areas and will identify changes and trends and their causes. The first topics addressed by the national synthesis are pesticides, nutrients, volatile organic compounds, and aquatic biology. Discussions on these and other waterquality topics will be published in periodic summaries of the quality of the Nation's ground and surface water as the information becomes available. This report is an element of the comprehensive body of information developed as part of the NAWQA Program. The program depends heavily on the advice, cooperation, and information from many Federal, State, interstate, Tribal, and local agencies and the public. The assistance and suggestions of all are greatly appreciated.

This report describes the subsurface distribution of reservoir units in rocks of Cambrian to Mississippian age in the central and southern parts of the Appalachian Plateaus province and evaluates their potential for storage of 1iquid waste. Areas of oil and gas resources, oil and gas wells, faults, tight folds, extensive fracture systems, seismic activity and the potential for the development of hydraulically induced vertical fractures need to be avoided when subsurface space is considered for injection and storage of liquid waste. 1 Potential reservoir intervals and potential confining intervals established in the study basin using this definition are grouped into six major potential reservoir units and seven major potential confining units. Many thanks are due Philip M. Brown for his continued interest, support and encouragement, and critical review of the manuscript even after his retirement from the U.S. Geological Survey.

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PLATE 1. Representative stratigraphic cross sections, Atlantic Coastal Plain, South Carolina and Georgia. 2. Geologic map of the Atlantic Coastal Plain, South Carolina and Georgia. A. Structural top of the pre-Unit H(?) basement surface. B. Thickness, Units F through H(?). C. Thickness, Units A through E. 3. Geohydrologic maps, Unit H(?) of Cretaceous and Late Jurassic(?) age, Atlantic Coastal Plain, South Carolina and Georgia. A. Structural top of Unit H(?). B. Thickness and isochlor map, Unit H(?). C. Sand-shale distribution map, Unit H(?). 4. Geohydrologic maps, Unit G(?) of Cretaceous age, Atlantic Coastal Plain, South Carolina and Georgia. A. Structural top of Unit G(?). B. Thickness and isochlor map, Unit G(?). C. Sand-shale distribution map, Unit G(?).

The Ground Water Atlas of the United States presents a comprehensive summary of the Nation's ground-water resources, and is a basic reference for the location, geography, geology, and hydrologic characteristics of the major aquifers in the Nation. The information was collected by the U.S. Geological Survey and other agencies during the course of many years of study. Results of the U.S. Geological Survey's Regional Aquifer-System Analysis Program, a systematic study of the Nation's major aquifers, were used as a major, but not exclusive, source of information for compilation of the Atlas.The Atlas, which is designed in a graphical format that is supported by descriptive discussions, includes 13 chapters, each representing regional areas that collectively cover the 50 States and Puerto Rico. Each chapter of the Atlas presents and describes hydrogeologic and hydrologic conditions for the major aquifers in each regional area. The scale of the Atlas does not allow portrayal of minor features of the geology or hydrology of each aquifer presented, nor does it include discussion of minor aquifers. Those readers that seek detailed, local information for the aquifers will find extensive lists of references at the end of each chapter.An introductory chapter presents an overview of ground-water conditions Nationwide and discusses the effects of human activities on water resources, including saltwater encroachment and land subsidence.