The plate tectonics hypothesis provides new insight into interpretation of the geomorphic history of the Atlantic Provinces. The landscape of the continental margin was probably rejuvenated in Late Triassic and Early Jurassic times as a result of regional tectonic uplift and ramping associated with continental breakup. The development of some aspects of the present geomorphic expression appears to have begun as early as Late Jurassic time.
Uplift was followed by broad regional subsidence along the continental margin and adjoining ocean basin and appears to have persisted to at least late Tertiary time. Unconformities across the formations of the submerged Atlantic Coastal Plain were formed during the time of broad subsidence, and these geomorphic surfaces were probably developed by subaerial processes. The lower sea levels possibly resulted from eustatic change rather than from tectonic uplift, and were possibly controlled by tectonic events along the mid-oceanic ridges.