The most dramatic new discoveries about the structure of the Earth in recent years have been those arising from the investigations of the ocean floors and the deep structure of the Earth (as it now is) by geophysical means. For a long time, however, a much larger bulk of information has been accumulating from the investigations of the continental masses; moreover, this information generally yields evidence of successively earlier stages in tectonic history. It is clearly essential in elaborating geotectonic hypotheses to take into account all the relevant evidence, and failure to do so may, in large measure, be attributed to the difficulty of searching through an enormous bulk of literature on continental tectonics and also to the subjective way in which much of it appears. It therefore seemed appropriate and timely to make available tectonic data aiming at a convenient and essentially objective presentation <...>
