Antler orogeny Antler orogeny in detail and somewhat refined its age span: "During the Antler orogeny, formations in Battle Mountain ranging in age from Ordovician to Mississippian (?) were complexly folded and faulted. As these rocks are unconformably overlain by the Battle Formation of Early Pennsylvanian (Des Moines) age, the orogeny probably took place during the Late Mississippian. The orogeny may have continued into Early Pennsylvanian, however, for the coarse conglomerates of the Battle Formation indicate derivation from a rugged highland area." In a subsequent influential paper, Roberts and others adjusted the age of the Antler orogeny as follows: "This belt is
Grenville orogeny the Highlands to the southeast and the Lowlands to the northwest. It is believed that the shear zone (the Carthage-Colton) was a transpressional boundary during the Ottawan, when the Highlands were thrust over the Lowlands. The Grenville province is named for the village of Grenville in Quebec, and constitutes the youngest portion of the Canadian Shield. Since the area has not undergone any regional metamorphic overprinting since the orogeny, it is considered an ideal study area for Grenville and pre-Grenville age tectonics. Hence, most of what is known about the orogeny and its processes is derived from the Grenville Province.