Abstract Mesozoic rocks of Atlantic Canada (New Brunswick, Nova Scotia, Prince Edward Island, and Newfoundland) are mainly red continental clastic rocks, tholeiitic basalts, and mafic dykes of Triassic and Early Jurassic age. They occur throughout the Bay of Fundy area and locally at Chedabucto Bay (Fig. 6.1), and form sequences up to 3500 m thick in faulted graben; the Fundy Graben and Chedabucto Graben (formerly the Cape Split Trough of Poole et al., 1970). Mafic dykes are more extensive and occur beyond the boundaries of the graben; (Fig. 6.2). Cretaceous rocks include small alkaline intrusions at Notre Dame Bay, Newfoundland and Ford's Bight, Labrador as well as local unconsolidated clay and sand deposits in central Nova Scotia (Fig. 6.1, 6.2) and minor breccias at Ford's Bight. The Mesozoic rocks are related to the early stages of rifting and drifting that led to the opening of the Atlantic Ocean, and they overlie a wide variety of Paleozoic rocks related to the Appalachian or Iapetus cycle of orogenesis. The Fundy Graben is typical of Newark-type graben repre- sented along the length of the Appalachian Orogen as well as offshore (Williams, 1978a). It is bounded by faults and sited, in part, above a deep Carboniferous basin (Minas Basin), in turn parallel to the major Avalon-Meguma zone boundary. Over 150 years have passed since publication of the first report (Jackson and Alger, 1829) on Mesozoic rocks of Atlantic Canada. Many scientists have worked on these rocks over the years but the comprehensive observations of Powers (1916)