Since the time of Élie de Beaumont and the promulgation of his somewhat fantastic pentagonal theory of the arrangement of mountain chains, the attention of geologists has been largely withdrawn from the orientation of earth features and focused on the areal distribution of geologic formations and the construction of geologic sections. It must be admitted on all sides that to this transference of effort has been due the great advance which geology has made in the period which has since elapsed. The question may now be asked, however, whether the accumulation of geologic data and the replacement of the crude maps of the earlier period by the accurate modern topographic map do not warrant a return, if not to the methods of de Beaumont, at least to a new and entirely different study of the orientation of surface features. May not too much attention be now directed to . . .