Orogeny process whereby new mountains and other land-forms were thrust up, or else there would eventually be no land; he suggested that marine fossils in mountainsides must once have been at the sea-floor. Orogeny was used by Amanz Gressly (1840) and Jules Thurmann (1854) as "orogenic" in terms of the creation of mountain elevations, as the term "mountain building" was still used to describe the processes. Elie de Beaumont (1852) used the evocative "Jaws of a Vise" theory to explain orogeny, but was more concerned with the height rather than the implicit structures created by and contained in orogenic belts. His
Colorado orogeny Central Plains orogeny. The boundary between the Colorado orogeny and the Wyoming craton is the Cheyenne belt, a 5-km-wide mylonitic shear zone that verges northward. The Cheyenne belt transects and cuts off the south edge of the older Trans-Hudson orogeny. The Paleoproterozoic volcanic and sedimentary rocks that resulted from the Colorado orogeny underwent metamorphism followed by plastic folding under moderate pressure and temperature (PT) conditions (temperature about 500 °C and pressures in excess of 1.2 GPa). The metamorphism was accompanied by intrusion of intermediate calc-alkalic rocks, such as the granodiorites of the Boulder Creek batholith. The accompanying amphibolite facies metamorphism