Part III.—Geologic Implications
GENERAL REVIEW AND DISCUSSION
During the years the senior author worked in the Atlantic and Gulf Coastal Plain from Long Island to the Rio Grande (1898–1904) a good deal of time was spent puzzling about the origin of the continental shelf and the steep declivity beyond it, not only of the part along the Atlantic Coast, where the latest important fossiliferous deposits are Miocene, but also the part along the Gulf Coast, where there are important marine deposits that are still younger. As more facts were accumulated, the more firmly it was felt that there was no reasonable basis for the suggestion that the edge of the continental shelf along the Atlantic and Gulf coasts was connected with faulting.
On the other hand, it was clear that the Coastal Plain deposits had been laid down on a peneplaned surface of older beds and that the deposition had been initiated by the seaward tilting of this early Cretaceous peneplain (Fig. 11). The demonstrated slope of the peneplaned surface beneath the Coastal Plain beds in the Long Island-New Jersey regions was such that it showed that the beds in which the Hudson Submarine Canyon was cut were of Tertiary and Cretaceous age. The total thickness of 10,000 to 15,000 feet, thus indicated for the Cretaceous and Tertiary beds off the coast of Long Island and New Jersey, seemed large when compared with the sections along the narrow belt above the present sea level, but it was found not to be unreasonable . . .