Status of geological and geophysical investigations on the Atlantic and Gulf Coastal Plain
Major features of the structure of the Gulf and Atlantic Coastal Plain of the United States are summarized. They include a postulated geosyncline of proportions comparable to those of the Appalachian of Paleozoic time. The attitude of the basement floor in Arkansas and along the Atlantic coast as inferred from wells which penetrated it and geophysical data on basement configuration are discussed, with emphasis on seismic methods. Seismic velocities in the basement rocks and younger sediments, possible depth limitations of the seismic method, and tests of the method are described. Seismic investigations on the Atlantic Coastal Plain are reviewed, with special reference to work at sea near the edge of the continental shelf, where attempts to map the basement rocks gave inconclusive results.