In 1966 after the International Indian Ocean Expedition, it was clear to the scientists who had participated therein that the amount of new information collected concerning the structure of the ocean bed was so extensive that the best way to make this information accessible to a broad range of scientists would be to compile a special geological/geophysical atlas. This was the first attempt to compile such a specialised atlas. In accordance with a decision reached by the Intergovernmental Oceanographic Commission the Soviet Union was entrusted with the task of publishing such an atlas, as an international co-operative effort. Preparation of the atlas was subsequently carried out under the supervision of an international editorial board by a large number of contributors from many different countries over the years 1966-1975. The Geological/Geophysical Atlas of the Indian Ocean that was published in 1975 met with the approval of the scientific community and gave rise to a plan to Produce similar atlases of the Atlantic and Pacific Oceans. Admittedly these two oceans had already been studied in significantly more detail than the Indian Ocean and compilation of the next two atlases did not involve a similar period of intensive international effort to gather material, such as that of the International Indian Ocean Expedition, nor was there therefore any agreed deadline for completion of the analysis of the research results. Nevertheless the proposal to compile and publish International Geological/ Geophysical Atlases of the Atlantic and Pacific Oceans, submitted by the Soviet Geophysical Committee of the USSR Academy of Sciences was accepted by the Intergovernmental Oceanographic Commission after receiving support from the Scientific Committee on Oceanic Research (of ICSU). The plan was ratified by IOC Resolution X-14 in November 1977. Some years however were necessary before financial problems could be settled and it was only possible actually to start work on the plan to compile these atlases in 1981, after the USSR Ministry of Geology had agreed to finance the preparation of the atlases and their final publication on the basis of a Contract drawn up with the Main Administration of Geodesy and Cartography under the Council of Ministers of the USSR. The main idea behind the compilation of these new atlases was to bring together the large amount of data which had already been gathered by research scientists but had still to be published or had only been published on a small scale often with a fair amount of interpretation. The extremely rapid-development of the technology used for marine scientific research in the years since the Second World War had given rise to a whole avalanche of new data on the structure of the ocean floor, and brought about a revolution in the understanding of tectonics of the Earth's ocean basins; it had given rise to the concept of a new global tectonics - the so-called 'plate tectonics'. Yet research thinking cannot mark time and new data are essential for it to advance. Careful study of factual data and their critical analysis and synthesis are only possible if they become accessible in a form that is convenient for purposes of analysis. Precisely such a form is provided when primary data are published with a minimum of interpretation, on a large scale and with wide use of graphics, this involves in particular the use of colour in atlases such as the Geological/Geophysical Atlas of the Indian Ocean. This main idea complements the need to illustrate the new technical equipment and methods used in research, providing examples of their application. It was decided that the content of the new atlases would, broadly speaking, be the same as that used in the Geological/Geophysical Atlas of the Indian Ocean, but with a few changes reflecting the degree to which these other two oceans had so far been studied. The history of the study of the oceans and the development of our understanding of the relief of the ocean floor is illustrated by fragments of old maps. A special section contains information on a selection of the main research vessels from which the work on advancing the study of the oceans has been carried out since the science of oceanography was in its infancy.This is followed by a section on information concerning new research methods for the study of the geology and geophysics of the ocean floor, and also information on the methods used for compiling some of the maps contained in the atlases. The main selection of maps on scales of 1:10 million (at 45 latitude) Mercator Projection, and 1:30 million Transverse Equal Area Projection of the Central Scientific-Research Institute of Geodesy, Aerophotography and Cartography (TSNIIGAiK), contains materials on the relief of the ocean floor, the magnetic total intensity anomalies, gravity anomalies, sea surface heights, geothermal data, seismicity, the deep structure of the earth's crust, the thickness of sediment cover, types of sediments, nature of basement and on the results of deep-sea drilling. This selection is supplemented by more detailed maps illustrating certain areas that are particularly interesting from the geological point of view, or which have been subjected to particularly detailed study on a larger scale (Mercator projection). There is a list at the end of the Atlas of the original sources,used by the authors for map-compilation. The team of contributors included specialists from many countries well known for their work on the study of the oceans. As a rule there was a Curator co-ordinating the work of individual contributors in charge of each group working within a particular field. The Editorial Board set itself the goal of ensuring that all contributors presented their data in as much detail and in as objective a way as possible. With this end in mind, annual meetings of the Editorial Board were held from 1981 onwards, whenever the quantity of material gathered made it necessary; after 1984 these meetings were supplemented by occasional intercessional consultations. Large numbers of contributors came together for both the meetings and the consultations. The contributors' original materials were collected and approved by the Editorial Board and then handed over to the Mapping Production Association where, under the supervision of Dr. D.l. Zhiv, one of the members of the Editorial Board, the original maps were prepared for final publication. The originals, and later black & white and colour proof stages of preparation through which the material; passed prior to publication, were presented to the Editorial Board to be checked and edited. Preparation of the final authors' originals was completed by the end of 1987 and as a result the atlas will reflect the level of knowledge relating to the geology and geophysics of the Atlantic Ocean attained by the period 1984-1987. All maps submitted earlier have wherever, possible been supplemented with data that had become available by 1987. The compilation of this atlas represents without doubt a major achievement of international co-operation, the spirit of this co-operatior made itself felt in the exchange of data gathered by contributors from the various countries involved, in their joint analysis of the data ant in the support given to this work by the governments, authorities, institutes and individual scientists taking Dart in the project. The Editorial Board wish to acknowledge the considerable help and support provided by I N.P. Budnikov I (Ministry of Geolog of the USSR), V.V. Belousov (Soviet Geophysical Committee, USSR Academy of Sciences) and V.G. Sedov (Intergovernmental Oceanographic Commission of UNESCO). EDITORIAL BOARD The atlas project, including content and layout, was developed by the Editorial Board in consultation with the Mapping Production Association of the Main Administration of Geodesy and Cartography under the Council of Ministers of the USSR.