Most of the Blue Ridge in the park area consists of granite and granodiorite which intrude Catoctin volcanic rocks. The granite and granodiorite are closely related, but most of the granite is a later facies. The pre-Cambrian age of all these rocks may be demonstrated in this area. Older schists and gneisses have been almost completely assimilated by the intrusive mass along the crest of the Blue Ridge. Lower Cambrian lava flows occur along the west side of the Blue Ridge in the park area.
The granite and granodiorite are here correlated with the Corbin granite of Georgia, which, as G. W. Crickmay has shown, intrudes the Pinelog formation of the Talladega series. It is suggested that long-range correlation of other igneous types in the Appalachian region may be possible and that such studies may lead to some reinterpretation of the geologic history.
The only Paleozoic sedimentary formations in the . . .