Alleghanian orogeny the Allegheny and Cumberland Plateau, which in some areas are popularly called mountains, but are actually simply uplifted and eroded plateaus. A portion of the Alleghanian mountain system departed with Africa when Pangaea broke up and the Atlantic Ocean began to form. Today, this forms the Anti-Atlas mountains of Morocco. The Anti-Atlas have been geologically uplifted in relatively recent times, and are today much more rugged than their Alleghanian relatives. Alleghanian orogeny The Alleghanian orogeny or Appalachian orogeny is one of the geological mountain-forming events that formed the Appalachian Mountains and Allegheny Mountains. The term and spelling Alleghany orogeny was
Antler orogeny some of the classic features of orogeny as commonly defined such as metamorphism, and granitic intrusives have not been linked to it. In spite of this, the event is universally designated as an orogeny and that practice is continued here. This article outlines what is known and unknown about the Antler orogeny and describes three current theories regarding its nature and origin. There are two principal facies of lower Paleozoic rocks in Nevada. In the eastern part of the state, a north-trending fossil-rich carbonate shelf of Ordovician to Devonian age, termed the carbonate or eastern assemblage, gives way westward to