Avalonian Orogeny

A mountain-building event that affected the eastern portion of the Appalachian Geosyncline in late Precambrian time (Precambrian time occurred from 3.96 billion to 540 million years ago). Evidence for the orogeny consists of igneous intrusions, folding of strata, and the development of angular unconformities in the Avalon Peninsula of Newfoundland, the eastern portion