Sevier orogeny region which caused folding and thrusting. The mountains that were formed as a result were located in western Utah and eastern Nevada. The size, shape, and depth of the thrust faults created in the Sevier event are determined by seismic studies and deep well data because they are mostly still buried by overlying rock and sediment. The Sevier and Laramide orogenies ended when subduction along the western edge of North America was overcome by western extension of the North American Plate to start the Basin and Range Orogeny. The well known and familiar Basin and Range faults cut the older
Cadomian Orogeny de Tréguier" and "Ignimbrites de Lézardrieux". The southern edge of the Gulf of Saint-Malo between Tregor and Cancale shows the deformational structures of the Cadomian Orogeny. These are East-west to North East trending upright folding. Schistosity is developed parallel to the axial plane of the folds. Prehnite-pumpellyite facies to mid-amphibolite facies have been produced by metamorphism. Movement was concentrated in shear belts such as at St Cast. The movement on the belts was sinistral and horizontal. During the orogeny the migmatite belts of north east Brittany were formed. Baie de St Brieuc and St Malo migmatites were deformed with the