Orogenesis as the fundamental geological process

comparison is made between the different approaches to the study of the Earth by the field geologist and by the physicist interested in broad terrestrial problems On one hand, the rapid increase in geological knowledge is giving an increasingly clear picture of the progress of geological history and the nature of the processes which have been involved. On the other hand, the application of new and rapid methods of obtaining measurements of physical properties of the Earth are serving to limit and direct physical speculation about the nature of the Earth's mechanisms. These different approaches must lead to the same conclusion. When reached, it will be a history of the Earth and an explanation of its processes satisfying both to the geologist and to the physicist. Progress is such that some preliminary agreement upon the most basic processes should soon be possible. It seems that the forces causing orogeny are fundamental, and some conclusions can already be drawn from the rates at which certain processes have been operating. Estimates of the limits in rate of erosion since Mesozoic time are made, as well as estimates of the present rate of volcanism. It is suggested that these rates are such as to suggest strongly that the continents themselves, like the atmosphere and oceans, have grown in situ during the course of geological time.