The higher elevations are mostly either Archean or Paleozoic formations projecting above Tertiary deposits.
The crystallines are confined to the portion of the belt east of the Great Valley where Paleozoic rocks are always highly metamorphosed and occur for the most part in limited patches, excepting in New England and Canada, where they assume greater areal importance, and are besides very generally intruded by granites.
The Paleozoic sediments, ranging in age from Cambrian to Permian, occupy the Great Valley, the Valley Ridges and the plateaus still farther west.
==Geology== The rocks of the Appalachian belt fall naturally into two divisions; ancient (pre-Cambrian) crystallines, including marbles, schists, gneisses, granites and other massive igneous rocks, and a great succession of Paleozoic sediments.
Cretaceous Jurassic N k Bodorno :s: Vladikaukaz Lars `n - - - n ° Tiflis a =Plain of Vladikaukaz; b= Upper Jurassic; Moraine terrace; d= Folded lias shales; e = Upper Jurassic; = Paleozoic schists; Creenstone dykes; h= Granite; g°= Gneiss; i = Andesites; k = Jurassic?; I = Pliocene fNagelfluh); m = Miocene; 11 = Oligocene; r = Nullipore limesto n e & conglomerate.
The mountains are composed in great part of Paleozoic strata, often modified by vulcanism and greatly denuded and sculptured by wind and water erosion.