Studies of the distribution, thickness, and general character of sedimentary rock formations furnish ground for certain lines of attack on problems of continental tectonics and evolution. For example, from observation of the contrast in the total thickness and structure of rock strata in various mountain belts as compared with broad lowland regions of the continents the concepts of geosyncline and stable platform have been mainly derived. Both in geosynclinal and in stable platform areas, unconformities and the shallow water or subaerial character of the sedimentary deposits appear to indicate that subsidence of the underlying crust approximately kept pace with the rate of sedimentation. Stratigraphic and areal distribution of different clastic sediments indicates in certain cases that the chief sources of these materials were elongate tracts that were periodically upraised more or less strongly. These are geanticlines, parallel to and adjoining the geosynclines.
The purpose of this paper, which gives . . .