One point should be emphasized at the outset: the definition of the continental shelf under international and federal law has no relationship to the geologic definition. To the geologist the continental shelf starts with the upland coastal plain and extends seaward to the brink of the continental slope which typically occurs at approximately 200 meters (656 feet).1/ From the standpoint of international law, however, the continental shelf begins at the seaward limit of the territorial sea, at least three miles from the low-water mark of the coastline, and extends to a depth of 200 meters and possibly far beyond, depending upon the technological exploitability of the area in question.2/ Figure I shows a typical section of the continental shelf in profile.
The Outer Continental Shelf Lands Act, which is the federal vehicle for the mineral development of the nation's offshore areas, incorporates the broad scope of international law in providing that it is applicable to "all submerged lands lying seaward and outside of [state-owned lands] and of which the subsoil and seabed appertain to the United States and are subject to its jurisdiction and control."3/ Both the international and the federal definitions may include, therefore, areas that would be known to the geologists as continental slope, continental rise, and continental borderlands, rather than continental shelf.4/ It is in this broad sense of a submarine area over which the coastal state has jurisdiction that the terms "continental shelf" or "outer continental shelf" will be used, the latter term being simply a reference to the continental shelf of the United States.5
Because the continental shelf begins at the point where the territorial sea terminates, the effects of the Convention on the Territorial Sea and Contiguous Zone which was incorporated into the domestic law of this country is very significant.6/ Figures 2, 3 and 4 show the application of the criteria of such Convention in determining the limits of the territorial sea.
It is clear that prior to 1945 there was no internationally recognized appropriation or right of appropriation to submarine areas outside of a nation's territorial sea, whether the same were continentalshelf or otherwise. There was a great deal of interest, particularly in the United States, regarding the offshore development of oil and gas but it was directed largely to lands underlying the territorial sea, the three-mile coastal belt. In 1945, however, President Truman issued his landmark proclamation in which he expressed the view that "the exercise of jurisdiction over the natural resources of the subsoil and sea bed of the Continental Shelf by the contiguous nation is reasonable and just" and proclaimed
"... the Government of the United States regards the natural resources of the subsoil and sea bed of the continental shelf beneath the high seas but contiguous to the coasts of the United States as appertaining to the United States [and] Subject to its jurisdiction and control."7/
The Truman Proclamation, which is set forth in full in Appendix A, gave impetus to a number of claims by other coastal states of submarine areas as "continental shelf" but there was a decided lack of uniformity in them.