The perfection and use of new methods of marine surveying in offshore regions, so much more rapid and accurate than methods available hereto- fore, have added a continually increasing store of accurate data on the submerged continental margins of the United States and possessions. The comprehensive surveys made by the Coast and Geodetic Survey since 1930 have covered the whole of the northeastern coast of the United States from the eastern end of Georges Bank nearly to Cape Hatteras. These surveys extend to distances ranging from 115 to 180 miles offshore and to depths as great as 1650 fathoms (9900 feet). During the same period comparable sections of the Gulf coastal waters, the Pacific Coast of California, Washington, and vast areas in Alaskan waters have been surveyed by the same accurate methods.
It was realized several years ago by Coast Survey engineers that the evergrowing use of echo sounders and further perfection of depth- and position-finding methods would require a treatment different from the old procedure of handling the field data and charting methods; certain studies were made as early as 1933 with a view to getting more of the new data on charts in a manner satisfactory to mariners. But due to circumstances beyond control of the Coast Survey there appeared to be little chance that the mass of new data would be published in full and in the form necessary for special studies for a considerable period of years. It seemed to the writer that at least some of these new accurate data should be made available to interested scientists without delay and published in such form, on a sufficiently large scale, that anyone could have all the available facts. The heads of the divisions of the Coast and Geodetic Survey directly concerned most heartily agreed, and the Geological Society of America made a grant to the writer from its Penrose Bequest to defray the cost of preparing the necessary plates showing thousands of soundings in their correct positions and the other expenses necessary in handling such a project. Work was begun late in the spring of 1937. The amount of data in the records, but not yet on the "smooth" sheets, exceeded expectations. Consequently more topographic detail was found than originally anticipated. While the preparation of the charts has taken much more time than was estimated, this delay has made possible the incorporation of all the 1937, 1938, and 1939 surveys in deep water.
The result of this cooperation has been the preparation and, with the issuance of this Special Paper, the publication of charts covering four . . .