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Since its inception modern geology has been faced with an important group of problems: explaining parallel formations that are separated by great distances of sea; accounting for isolated life forms in widely separated areas (such as lemurs in Madagascar and India); explaining pre-pleistocene glaciations, and similar problems. The usual explanation has been to assume the one-time existence of land bridges (such as the hypothetical Lemuria) or parallelisms or diffusion with lost ...
Since its inception modern geology has been faced with an important group of problems: explaining parallel formations that are separated by great distances of sea; accounting for isolated life forms in widely separated areas (such as lemurs in Madagascar and India); explaining pre-pleistocene glaciations, and similar problems. The usual explanation has been to assume the one-time existence of land bridges (such as the hypothetical Lemuria) or parallelisms or diffusion with lost intermediary steps.
In 1915, however, one of the most influential and most controversial books in the history of science provided a new solution. This was Alfred Wegener's Entstehung der Kontinente, which dispensed with land bridges and parallel evolutions and offered a more economical concept. Wegener proposed that in the remote past the earth's continents were not separate (as now), but formed one supercontinent which later split apart, the fragments gradually drifting away from one another. Wegener created his supercontinent with attractive simplicity by tucking the point of South America into the Gulf of Guinea, coalescing North America, Greenland, and Europe, rotating Australia and Antarctica up through the Indian Ocean, and closing the remaining gaps. Wegener then explained various phenomena in historical geology, geomorphy, paleontology, paleoclimatology, and similar areas of science in terms of this continental drift. To back up his revolutionary theory he drew upon a seemingly inexhaustible find of data. Later editions of his book added new data to refute his opponents or to strengthen his own views in the violent scientific quarrel that arose.
Even today this important question remains undecided, and geologists are divided into strongly opposed groups about the Wegener hypothesis. At the moment it seems to be gaining steadily in acceptance. It is one of the two basic theories of earth history, and since it has often been misrepresented in summary, every earth scientist owes it to himself to examine its theories and data.
THE BACKGROUND to this book may not be wholly without interest. The first concept of continental drift first came to me as far back as 1910, when considering the map of the world, under the direct impression produced by the congruence of the coastlines on either side of the Atlantic. At first I did not pay attention to the idea because I regarded it as improbable. In the fall of 1911, I came quite accidentally upon a synoptic report in which I learned for the first time of palæontological evidence for a former land bridge between Brazil and Africa. As a result I undertook a cursory examination of relevant research in the fields of geology and palæontology, and this provided immediately such weighty corroboration that a conviction of the fundamental soundness of the idea took root in my mind. On the 6th of January 1912 I put forward the idea for the first time in an address to the Geological Association in Frankfurt am Main, entitled "The Geophysical Basis of the Evolution of the Large-scale Features of the Earth's Crust (Continents and Oceans) " ("Die Herausbildung der Grossformen der Erdrinde (Kontinente und Ozeane) auf geophysikalischer Grundlage"). A second address followed, this one on the 10th of January, delivered before the Society for the Advancement of Natural Science in Marburg under the title "Horizontal Displacements of the Continents" ("Horizontal-verschiebungen der Kontinente"). In the same year, the two first publications also appeared [1, 2]. Further work on the theory was prevented by my participation in the crossing of Greenland led by J. P. Koch in 1912/1913, and later by war service. However, in 1915 I was able to make use of a prolonged sick-leave to furnish a rather more detailed account, with the same title as this volume and published by Vieweg . When, after the end of the war, a second edition (1920) became necessary, the publisher was kind enough to transfer the book from the Sammlung Vieweg to the Sammlung Wissenschaft (Science Series); this made a more thoroughgoing revision possible. In 1922 appeared the third edition, again fundamentally improved, and in an unusually large printing so that I could work on other problems for a few years. It has been completely out of print for some time. A series of translations of this edition appeared, two Russian, one English, one French, one Spanish and one Swedish. I undertook to make a few changes in the German text for the Swedish translation, which appeared in 1926.
This fourth edition of the German original has once again been thoroughly revised; in fact, it has taken on an almost totally different character from its predecessors. When the previous edition was being written, there was already a comprehensive literature on continental drift which had to be taken into account. However, this literature was confined in the main to expressions of agreement or disagreement and to the citing of individual observations which spoke out or appeared to speak out either for or against the correctness of the theory; whereas since 1922, not only has the discussion of this question within the different earth sciences grown out of all proportion, but the very character of the discussion has altered to some extent. The theory is being used more and more as a basis for more extensive investigations. In addition, there is the recent precise evidence for the present-day shift of Greenland, which for many people has probably placed the discussion on a completely new footing. Therefore, while the earlier editions contained in essence merely a presentation of the theory itself and a collection of the individual facts in support of it, the present edition represents a transitional stage between the mere presentation of the theory and a synoptic exposition of these new branches of research.
Even when I was first occupied with this question, and also from time to time during the later development of the work, I encountered many points of agreement between my own views and those of earlier authors. As far back as 1857 Green spoke of "segments of the earth's crust which float on the liquid core" . Rotation of the whole crust—whose components were supposed not to alter their relative positions—has already been assumed by several writers, such as Löffelholz von Colberg , Kreichgauer , Evans and others. H. Wettstein wrote a book  in which (besides many inanities) the idea of large horizontal relative displacements of the continents is to be found. In his view, the continents—whose shelves he did not take into account—undergo not only displacement, but also deformation; they all drift westwards under tidal forces of the sun acting on the viscous material of the earth (an idea also held by E. H. L. Schwarz ). However, Wettstein, too, regarded the oceans as sunken continents, and he expressed fantastic views, which we pass over here, on the so-called geographical homologies and other problems of the earth's surface. Like myself, Pickering started out from the congruence of the southern Atlantic coastlines in a work  in which he expressed the supposition that America had broken away from Europe-Africa and was dragged the breadth of the Atlantic. However, he did not observe that one must in fact assume that an earlier connection between the two continents existed during their geological history up to the Cretaceous period, and he therefore assigned this connection to a dim and distant past, believing the breakaway to be bound up with G. H. Darwin's assumption that the moon was flung from the earth, and that traces of this can still be seen in the Pacific basin.
In a short article in 1909 Mantovani  expressed some ideas on continental displacement and explained them by means of maps which differ in part from mine but at some points agree astonishingly closely: for example, in regard to the earlier grouping of the southern continents around southern Africa. It was pointed out to me in correspondence that Coxworthy, in a book which appeared after 1890, put forward the hypothesis that today's continents are the disrupted parts of a once-coherent mass . I have had no opportunity to examine the book.
I also discovered ideas very similar to my own in a work of F. B. Taylor's  which appeared in 1910. Here, he assumed by no means inconsiderable horizontal shifts of the individual continents in Tertiary times, and connected these with the large Tertiary systems of folding. He came to virtually the same conclusions as my own, for example, about the separation of Greenland from North America. In the case of the Atlantic, he assumed that only part of its width is due to drag displacement of the American land mass and that the rest is due to submergence and constitutes the mid-Atlantic ridge. This viewpoint, too, differs only quantitatively from my own, but not in crucial or novel ways. For this reason, Americans have sometimes called the drift theory the Taylor-Wegener theory. However, I have received the impression when reading Taylor that his main object was to find a formative principle for the arrangement of the large mountain chains and believed this to be found in the drift of land from polar regions; my impression is therefore that in Taylor's train of thought continental drift in our sense played only a subsidiary role and was given only a very cursory explanation.
I myself only became acquainted with these works—including Taylor's—at a time when I had already worked out the main framework of drift theory, and some of them I encountered much later on. It is of course not beyond the bounds of possibility that further works will be discovered in the course of time which will prove to contain elements of agreement with drift theory or to have anticipated a point here or there. Historical investigations have not been undertaken as yet and are not intended in the present book.
Excerpted from The Origin of Continents and Oceans by Alfred Wegener, John Biram. Copyright © 1966 Dover Publications, Inc.. Excerpted by permission of Dover Publications, Inc..
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