A generalized summary of Appalachian orogenic events starts with an epoch of mountain building that occurred before the Cambrian period began and produced an eastern highland from which most Cambrian clastics were derived. From the middle of the early Cambrian to at least the beginning of the Mid-Ordovician, there are no evidences of any contemporaneous Appalachian mountain building. The eastern highlands were essentially destroyed by erosion before the middle of the Cambrian, and Cambro-Ordovician carbonate rocks testify to a continental-shelf site of deposit instead of a geosynclinal site as is commonly assumed.

Commencing in the Mid-Ordovician with the uplift of low positive axes and heralded by volcanic activity that produced widespread beds of bentonite, a great and vigorous earth movement affected the Appalachian country and the eastern border of what is now the North American continent. From the onset of the Silurian to the end of the Paleozoic, there was probably no time when this wide area was completely free from the effects of contemporaneous orogeny or vulcanism.

The chief pre-Silurian effort, known as the Taconic disturbance, must have been the most profound of all Appalachian orogenies—much more vigorous, more extensive, and more intense than any mountain building to follow in eastern North America. Most Devonian phases of deformation are associated with the Acadian disturbance of which the major effort, known as the Schickshockian disturbance, came during the middle and late Devonian for most areas of its influence.

The terminal Paleozoic or so-called “Appalachian” orogeny, here renamed the Alleghany revolution, variously affected parts of the Appalachian province from Mississippian time to the close of the era and may have continued into the early and early middle Triassic before it came to a final close.

The discussion briefly covers the sedimentary, structural, igneous, and metamorphic records of Appalachian folding.

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