Angular Unconformity, upstate New York.

Steeply dipping Middle Ordovician Austin Glen Formation (on right) overlain by moderately dipping Upper Silurian Roundout Formation. Their contact represents a period of erosion after tilting (folding) of the Austin Glen Formation. This period of folding was the Ordovician Taconic Orogeny. A still later period of deformation, the Acadian Orogeny, tilted (folded) the unconformity and overlying Roundout Formation during the Devonian Period.

Taconic Unconformity

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