Antler orogeny age of the Roberts Mountains thrust to coincide with the Late Devonian to Mississippian Antler orogeny and to extend the name far beyond the Roberts Mountains. Over a period of 22 years numerous reports relating the Antler orogeny and Roberts Mountains thrust to plate convergence were published in various journals, and because their basic tenets have been widely accepted, they are here termed the conventional theories. The earliest effort to relate plate tectonics specifically to the Antler orogeny was briefly outlined by E.M. Moores: "A collision of this continental margin with a subduction zone dipping away from it in late
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