Chapter I: Foreword

The diagrammatic portrayal of the relief of continental land areas of the world has been completed by both the late A. K. Lobeck and Erwin Raisz, whose magnificent diagrams are familiar to all geologists and geographers. The authors of the present sheet are preparing a similar series of marine physiographic diagrams.

_The Physiographic Diagram: Atlantic Ocean; Sheet 1_ is the first of this projected series. The Atlantic Ocean diagram will consist of five sheets at a scale of about 1:5 million. A diagram of the South Atlantic Ocean at a scale of about 1:11 million now nearly completed will form the first of a general series planned to portray the world oceans.

In addition, diagrams of selected areas well covered by sounding profiles will be prepared at scales of about 1:2 million.

Each sheet or series of sheets will be accompanied by descriptive notes treating the nomenclature, morphological, geological, and geophysical characteristics of each of the physiographic provinces.

_Lamont Geological Observatory Contribution 308_

NOTE

_Physiographic Diagram: Atlantic Ocean, Sheet 1 (Plate 1)_

Copies of the Physiographic Diagram: Atlantic Ocean, Sheet 1 are available unfolded so that each will be suitable for wall mounting. The diagram is therefore not physically inserted or attached to this volume although it forms the basic part of the paper.

ACKNOWLEDGEMENTS

The studies of submarine topography at the Lamont Geological Observatory have been supported by the United States Navy Bureau of Ships under Contract NObsr 64547. The expeditions which obtained topographic data were supported by the Office of Naval Research under Contracts N6 onr 27124 and N6 onr 27113 and the Bureau of Ships under Contract NObsr 64547. Three cruises were supported by the National Geographic Society, the Woods Hole Oceanographic Institution, and Columbia University. Financial support has been received from The Geological Society of America (Grant 635-54). The preparation of this paper was supported in part by the Bell Telephone Laboratories.

The studies that led to the present paper began at the Woods Hole Oceanographic Institution just after World War II. With the founding of the Lamont Geological Observatory in 1949 the work was transferred to that observatory at Palisades, New York. Topographic data from Woods Hole cruises were incorporated with Lamont data until 1953, when a separate program was established at Woods Hole by J. B. Hersey, and Columbia University acquired the VEMA as its own research vessel. Although Woods Hole data obtained between 1953 and 1957 have not been used in preparing sheet 1, arrangements recently concluded provide for the incorporation of past and future Woods Hole data in subsequent sheets of this series.

The soundings were read, compiled, and plotted by Morris Wirshup, the late Andrew Nelson, Ivan Tolstoy, G. Leonard Johnson, III, the authors, and several others. The profiles were plotted by M. Wirshup, Hester Haring, the authors, and several others.

The soundings were taken primarily on board the Research Vessels VEMA and ATLANTIS (Woods Hole Oceanographic Institution), but important sounding lines were obtained by the R/V ALBATROSS (Woods Hole Oceanographic Institution), M/V THETA, and R/V CARYN (Woods Hole Oceanographic Institution) and in the eastern Atlantic by the R.R.S. DISCOVERY (National Institute of Oceanography).

The following officers made outstanding contributions to the navigational plotting: A. K. Lane, the late A. Karlson, J. Pike, R/V ATLANTIS; D. Gould, the late F. S. Usher, D. Smith, V. Sinclair, H. Kohler, and K. Simonson, R/V VEMA; and the late A. Nelson, R/V VEMA and M/V THETA.

The echo sounders have been installed, maintained, and improved by B. Luskin, H. R. Johnson, A. Roberts, M. Landisman, C. Hubbard, H. Van Santford, M. Langseth, G. Sutton, and many others.

The entire scientific party of each of the more than 50 expeditions represented in the data of this paper took turns marking and adjusting the echo sounder, and all navigational officers on these expeditions took the fixes and kept the logs. To these sea-going scientists and mariners too numerous to list the authors are extremely grateful.

Soundings in the northeast Atlantic compiled by the British Admiralty Hydrographic Department were kindly provided by Cmdr. J. S. N. Pryor of that organization. Dr. M. N. Hill of Cambridge and Dr. G. E. R. Deacon of the (British) National Institute of Oceanography were instrumental in obtaining many of these valuable deep-sea soundings. Original sounding sheets of many areas were provided by the Coast and Geodetic Survey through the courtesy of Admiral A. Karo and Mr. G. F. Jordan.

B. Luskin's development of the Precision Depth Recorder and his continued research and development in echo-sounding equipment made it possible to obtain many of the detailed data of this paper.

The following expedition chief scientists conducted sounding surveys which have been incorporated in this paper: M. Ewing, J. L. Worzel, J. E. Nafe, I. Tolstoy, R. S. Edwards, G. R. Hamilton, C. L. Drake, B. Luskin, W. C. Beckmann, F. Press, J. Northrop, J. Hirshman, M. J. Davidson, R. J. Menzies, F. C. Fuglister, E. T. Miller, and B. C. Heezen.

The writers are grateful to the great number of scientists who encouraged them in this work and especially to those who offered suggestions and discussed the data and conclusions. We are particularly indebted to W. H. Bucher for discussions relative to tectonics, to David B. Ericson for problems relating to sediment distribution and analysis, and to C. O'D. Iselin and C. H. Elmendorf for general encouragement and support during the several years of this study.

CONTENTS

PAGE

ABSTRACT 1

PART 1. PREPARATION OF THE PHYSIOGRAPHIC DIAGRAM 3