Marine physiography of the U.S. Atlantic margin
Although the study of Atlantic continental margin physiog- raphy (Plate la) started with lead-line sounding data centuries ago, it was the development and automation of precision echo sounding in the second quarter of the twentieth century that fostered modern investigation and interpretation (Veatch and Smith, 1939; Emery and Uchupi, 1972). Bottom samples ga- thered in the last four decades have strongly influenced the ex- planations for the development of submarine topography (Field and others, 1979; Hollister, 1973; Knebel, 1981; Milliman and others, 1972; Schlee and Pratt, 1970). High-resolution seismic profiling, side-scan sonar, bottom photography, current meters, and submersibles have allowed more detailed examination and interpretation of selected areas. Key recent articles cited in this chapter, from the vast literature about the Atlantic margin, pro- vide references for an up-to-date understanding of the major physiographic features of the shelf, slope, and rise. In addition, controversies and unresolved questions have been identified. For readers less familiar with the location of physiographic features discussed in the text, the map provided should be of considerable assistance.
Because the nature of the shelf physiography and the proc- esses responsible for creating the submarine landforms differ markedly along the U.S. Atlantic shelf (Burk and Drake, 1974; Nairn and Stehli, 1974; Emery and Uchupi, 1972; and Uchupi, 1968), six areas are recognized. From north to south they are: 1) Gulf of Maine, 2) Georges Bank, 3) Southern New England,4) Mid-Atlantic from Rhode Island to Cape Hatteras, 5) South-Atlantic from Cape Hatteras to Southern Florida, and 6) the Bahamas. A seventh section introduces the recent literature on microtopography and related sediment transpont.
Figures & Tables
The Atlantic Continental Margin
This synthesis covers stratigraphy, depositional processes, and geophysical interpretation of the major onshore and offshore marginal basins from Maine to the Bahamas, and includes an up-to-date review of thinking on regional tectonic history. Additional chapters discuss the theoretical aspects of thermal evolution, subsidence, and seismic stratigraphy as applied to this region. Geological resources including petroleum, water, sand and gravel, hard minerals, and heat flow are reviewed, and environmental hazards such as seismicity, coastal erosion, waste disposal and submarine instability as it relates to site of drilling platforms and mining are evaluated. A summary chapter reviews areas of controversy and suggests key topics for research.