Marine Geology. Preface: The geologists of the past have not always developed their science systematically. The geology of the seas has been especially neglected, but with good reason. Most geological subjects are readily accessible, or relatively so, as respects time and money. The examination of the sea floor, however, means expensive and lengthy cruises as well as intricate techniques of investigation. Only recently have an increas ing number of individual workers, oil companies, and oceanographical institutions embarked on a more intensive study of marine geology. This neglect still prevails in teaching in spite of the fact that most undergraduates will later spend a major portion of their time dealing with fossil marine sediments in one way or another. As long as marine geology remained undeveloped, this lack of emphasis could be fully justified. However, now that great advances in this subject have been made there would seem to be ample reason for giving more attention to the geological problems of the sea. To this end, three purposes have been in mind while this book was being written. The first was to introduce university students of ge ology to an important branch of their subject. The second, to pro vide a guide for geologists, oceanographers, and scientists in general who wish to explore the field of marine geology, and, finally, to aid the advance of research by summarizing achieved results and empha sizing the many problems still to be solved. It should be realized that this is not intended as a source book for data, but references, although not complete, will point the way to whatever detailed information the reader may require. Throughout, emphasis has been laid on problems in the hope of stimulating the students interest and his critical faculties. I am well aware, however, that this approach may have led me to make sweep ing statements and to emphasize some subjects beyond their general significance, while neglecting others. Some subjects, such as geo physics of the sea floor, geomorphology of coastlines, descriptive petrography of recent marine sediments, and the analysis of fossil rock facies, have purposely been touched on only superficially. On the other hand I have given special attention to coral reefs, submarine canyons, and the Moluccan deep-sea troughs, having spent much time myself on these subjects. The present volume differs markedly from other recent textbooks dealing with marine geology. Dalys The Floor of the Ocean is mainly geophysical Bourcarts Geographie du fond des mers, geo graphical The Oceans by Sverdrup et al., oceanographical. Shep ards excellent Submarine Geology emphasizes geomorphological mat ters and field techniques, and there is surprisingly little duplication in our texts. Not until well along with the writing did I realize how wide and diversified is the field of marine geology. Had it not been for the generous assistance offered by several colleagues this book would never have been brought to completion. Foremost among these are C. O. Dunbar, who read the whole of the original manuscript, and F. P. Shepard, who read most of it. Both suggested a very substantial number of corrections and alterations. Others who read some chap ters and gave valuable advice are P. Groen, D. L. Inman, A. N. Jeffares, Gerda A. Neeb, L. M. J. U. v. Straaten, and J. H. F. Umb grove...