Surge tectonics is based on the concept that the lithosphere contains a worldwide network of deformable magma chambers (surge channels) in which partial magma melt is in motion (active surge channels) or was in motion at some time in the past (inactive surge channels). These surge channels play the role of the holes in the "hole-in-the-plate" problem ("elliptical hole problem") of civil and construction engineering, industrial engineering, and rock mechanics (Inglis, 1913; Donnell, 1941; Murrell, 1964a, 1964b; Jaeger and Cook, 1979; McCartan and Gettings, 1991). The presence of surge channels means that all of the compressive stress in the lithosphere is oriented at right angles to their walls. As this compressive stress increases during a given geotectonic cycle, it eventually ruptures the channels that are deformed bilaterally into kobergens (Fig. 2.15). Kobergens were named by Meyerhoff et al. (1992b) in honor of the Austrian geologist, Leopold Kober (1921, 1925, 1926). Kober observed that Alpide foldbelts have been bilaterally deformed with the northern ranges vergent toward Europe and the southern toward Africa (see Fig. 12 in Meyerhoff et aI., 1 992b). Thus, bilaterally deformed foldbelts in surge-tectonics terminology are called kobergens.
Surge tectonics involves three separate but interdependent and interacting processes. The first process is the contraction or cooling of the Earth. The second is the lateral flow of fluid, or semifluid, magma through a network of interconnected magma channels in the lithosphere. We call these surge channels for reasons that will become apparent. The third process is the Earth's rotation. This process involves differential lag between the lithosphere and the stricto sphere (the hard mantle beneath the asthenosphere and lower crust), and its effects---eastward shifts--- already discussed (Table 2.3). Because lithosphere compression caused by cooling is the mechanism that propels the lateral flow of fluid, or semifluid, magma through surge channels, we discuss first the velocity structure of the Earth's lithosphere and underlying layers, then the contraction hypothesis (Earth cooling), and then the effects of contraction on the Earth's outer shells.
AAM: Surge Tectonics: Earth has cooled and shrunk greatly and densification has caused continental lands to sink and magma surge channels have caused orogenesis.