Geochronology, and isotopic data bearing on development of the continental crust

I will present some ideas and problems regarding the evolution of the crust of the earth and will also attempt a prognosis of the application of isotopic techniques to the understanding of geological processes. This dissertation might well be entitled "Pride and Prejudice"; it will be my implicit assumption that the use of physicochemical techniques and principles, when used with a sound geologic knowledge, has and will help solve important existing problems and will also create new problems and new fields which are themselves an integral part of the science of geology.