In its classical sense "epigenesis" refers to all geological processes originating at or near the surface of the earth. It thus embraces all those phenomena which we associate with the land- scape; Perel'man has already written extensively on this subject. The landscape, in the physical sense, is controlled by the interac- tion of exogenic and endogenic agencies-on the one hand, the atmo- sphere, the wind, the rain, and other components of the weather, the forces of running water and the planetary controls of gravitational and tidal nature; and on the other hand the materials of the earth's...