The geologists of North America have for over a century been gathering facts in regard to the geology of the continent. It is only within recent years, however, that the great increase in numbers of working geologists has brought a knowledge of the geology of most of the continent. There are still large regions about which little is known; for instance, the central part of Canada and most of Mexico. The eastern part of the United States has been reasonably well known for a generation, but even there certain major features of deformation have only within the last decade been found to be systematic.
It is proposed in this inquiry to describe the chief periods of deformation and their effects on the continent, and to analyze them into their essential parts, both in regard to time and to space. From these elements certain relations may be found which, if . . .