Notre Dame Bay is on the northeastern coast of Newfoundland and contains the record of deposition within a lower Paleozoic eugeosynclinal belt. Early studies of the region revealed a thick sequence of Ordovician volcanic and sedimentary rocks. Stratigraphic interpretations have been hindered by lack of fossils and by complex structure. The Lukes Arm fault zone is a major E-W dislocation across which structural and stratigraphic correlations are questionable. Transcurrent right-lateral displacement along this fault zone is indicated to be on the order of tens of miles or more. Other major faults of unknown sense of displacement separate and repeat stratigraphic sequences. Pre-Ordovician rocks are almost unknown, and the nature of the basement is conjectural.

The Ordovician stratigraphy south of the Lukes Arm fault zone is discussed for each of three areas--New World Island, New Bay, and Badger Bay. Ordovician rocks north of the Lukes Arm fault zone are termed the "Lushs Bight terrane"; they are predominantly volcanic, but include minor sedimentary successions.

Cephalopod- and trilobite-bearing limestone of Tremadocian age is the oldest rock exposed in sequence. Shelly faunas are present in Llanvirnian-Llandeilan volcanic rocks and Llandoverian conglomerate. Caradocian graptolites are common in thin argillite sequences between lower volcanic rocks and higher graywacke. These faunules permit tentative correlations between areas where the Ordovician is exposed.

Early Ordovician history of the region was dominated by volcanism. Volcanic activity continued through the medial Ordovician in the southwest, and also north of the Lukes Arm fault zone. Elsewhere, the medial Ordovician was characterized by clastic deposition in a deeply subsiding trough. Extreme water depths are indicated by the presence of conglomeratic argillite, similar to argille scagliose, in the southeast. A second period of volcanism preceded intermittent argillite deposition in a quiescent Caradocian trough. The late Ordovician south of the Lukes Arm fault zone was marked by a synorogenic phase of flysch deposition. Graywacke became coarser and increasingly more prevalent near the end of the Ordovician. Plutonic clasts within polymictic conglomerate first appear in t e middle Caradoc rocks and attest to the denudation of tectonic lands perhaps raised by Ordovician intrusions. Conglomerate beds increase in abundance and thickness through the upper Ordovician and dominate the basal Silurian. In some areas deposition was continuous across the systemic boundry, but elsewhere a major unconformity appears to separate middle Ordovician strata from overlying Silurian conglomerate.