Major features of the earth's surface are its continents and its ocean basins--which in turn reflect fundamental differences between continental and oceanic crusts. The broad zone of separation, or junction, between the continental and oceanic domains has been called the continental margin. It particularly includes the seaward part of the continental shelf, the continental slope, and the landward part of the continental rise.

Many of the most exciting events in the history of our planet have been concerned with the interplay between continental and oceanic crust and between continents and oceans; and the continental margin represents the stage where, throughout earth history, this drama has been played.

Important elements of the continental margin are the outer shelf, the borderlands, the marginal plateaus, the slope, the base of the slope, the rise, and the marginal trenches. The origin of these features and the nature of their sediments and local structures are the essence of geology. Of particular interest to the petroleum geologist are also the sediment-rich semi-enclosed basins or seas associated world-wide with the continental margin, the barrier ridges and reefs so commonly developed near the rim of the continental slope, and the growing evidence for impressive vertical movements of basin floors.

Great advances in our understanding of the processes active at the continental margins have come from the subsea geological and geophysical studies of the last decades, and rapid additional progress may be expected from the stimulus of "the new global tectonics"; but current hypotheses are still largely in a developmental stage. Factual data are still woefully inadequate. Moreover, continuing studies are needed, not only of the present continental margins but also of the past continental margins.

For the petroleum geologist, it is significant that through the ages the continental margin has been the great mixing bowl in which has been brewed the bulk of the world's petroleum and from which the bulk of its petroleum production to date has been derived. The continental margin should be the fruitful meeting ground of the petroleum geologist, the geologist of the oceans, and the student of earth history.

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