_The Geological Society of America Special Paper 65_ THE FLOORS OF THE OCEANS I. THE NORTH ATLANTIC Text to Accompany the Physiographic Diagram of the North Atlantic BY BRUCE C. HEEZEN, MARIE THARP, AND MAURICE EWING _Lamont Geological Observatory (Columbia University) Palisades, New York_ [Illustration] April 11, 1959 _Made in the United States of America_ TEXT PAGES COMPOSED AND PRINTED BY THE WILLIAM BYRD PRESS COLLOTYPE PLATES PRINTED BY THE MERIDEN GRAVURE COMPANY LINE PLATES PRINTED BY WILLIAMS AND HEINTZ BOUND BY RUSSELL-RUTTER COMPANY PUBLISHED BY THE GEOLOGICAL SOCIETY OF AMERICA ADDRESS ALL COMMUNICATIONS TO THE GEOLOGICAL SOCIETY OF AMERICA 419 WEST 117 STREET, NEW YORK 27, N. Y. _The Special Papers Series Of The Geological Society of America is made possible through the bequest of Richard Alexander Fullerton Penrose, Jr._ _"Could the waters of the Atlantic be drawn off, so as to expose to view this great sea-gash, which separates continents, and extends from the Arctic to the Antarctic, it would present a scene the most rugged, grand, and imposing. The very ribs of the solid earth, with the foundations of the sea, would be brought to light, and we should have presented to us at one view the empty cradle of the ocean...." (M. F. Maury, The Physical Geography of the Sea, 1855.)_ 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