The Canadian Appalachian region includes the provinces of insular Newfoundland, Nova Scotia, New Brunswick, Prince Edward Island, and the southern part of Quebec along the south side of the St. Lawrence River (Fig. 1.1). It has an area of approximately 500,000 km2 and it is widest (600 km) at the Canada-United States International Boundary in New Brunswick and Nova Scotia. A larger unexposed area of Appalachian rocks and structures extends across the Gulf of St. Lawrence and seaward to the Atlantic continental edge. Because of its coastal setting and insular makeup, the region offers tremendous shoreline exposures along marine passages.
The Appalachian region is a Paleozoic geological mountain belt or orogen. This means that its rocks have been affected by orogeny, the combined effects of folding, faulting, metamorphism, and plutonism. Paleozoic folds and faults of several generations trend northeastward. Regional metamorphic rocks occupy continuous belts in interior parts of the orogen, and granitic batholiths are common throughout its length (Maps 1 and 2).
The word “Appalachian” was first used in a geographic context for the morphological mountains in the southeast United States. It has displaced the word “Acadian” formerly applied to this region of eastern Canada. In the present context, the word “Appalachian” is used for the geological mountain belt without regard for its morphological expression.
Like the Cordilleran and Innuitian orogens, the Appalachian Orogen occupies a position peripheral to the stable interior craton of North America (Fig. 1.2). Undeformed Paleozoic rocks of the craton overlie a crystalline Precambrian basement.
Figures & Tables
This volume focuses on the highly populated Canadian Appalachian region. The chapter on the East Greenland Caledonides stands alone and there is no attempt to integrate the geological accounts of the two far removed regions. Rocks of the Canadian Appalachian region are described under four broad temporal divisions: lower Paleozoic and older, middle Paleozoic, upper Paleozoic, and Mesozoic. The rocks of these temporal divisions define geographic zones, belts, basins, and graben, respectively. The area is of special interest because so many modern concepts of mountain building are based on Appalachian rocks and structures.