Abstract

Geophysical data available for the continental margins of North America, South America, Africa, and Europe are examined and summarized. Seismic reflection profiling provide much detail of the uppermost sedimentary cover; seismic refraction data delineate the broad outlines of the upper crustal layers; and gravity data restrict the choices of the deeper crustal structure and that of the upper mantle.Conclusions about the variability of the sedimentation at the various continental shelves, slopes, and rises are given. The transition zone between continental and oceanic structure is restricted to a narrow zone varying between 50 km and 300 km in width for various coasts. This transition zone is localized in the region of the 2000 m isobath for all the coasts studied. The continental margins are generally in isostatic equilibrium as a whole, although departing from this equilibrium somewhat, expecially in the transition zone.

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