This discussion of continental genesis is an attempt to formulate a consistent hypothesis of the origin and growth of continents.
A continent is defined as the outcrop of a mass which consists pre-dominantly, but not exclusively, of granitic rocks in contradistinction to suboceanic masses of basaltic rocks. Therefore the genetic processes which result in continents are considered to be eruptive and are traced in the interior reactions of the earth’s mass.
According to petrologic research, granitic rocks are differentiated from more basic magmas. Physical, chemical, and seismologic evidence indicates that the globe consists of an outer skin of diverse igneous rocks, a thick, solid shell of more basic rocks, and a dense, inelastic core, probably of iron. The inelastic condition of the last named is attributed to very high temperature. The most reasonable explanation of these conditions is found in the planetesimal origin of the globe, which is . . .