Raised Shoreline Phenomena and Postglacial Emergence in South-Central Newfoundland

Abstract

Two types of raised marine shoreline features occur in the Burin-Hermitage area of southern Newfoundland marine benches cut in bedrock, and terraces and beaches developed in unconsolidated materials. Most of the benches are older than Late Wisconsinan, and a horizontal rock shoreline at 4.5 ± 1.5 m, which occurs throughout the region, was probably formed in the last interglacial period. Raised deltas and coastal outwash deposits graded to former sea level positions, which define the Late Wisconsinan marine limit across the northern part of the study area, are correlated with terraces and raised beaches further south on the Burin Peninsula. The elevations of these features are used to define the regional pattern of postglacial emergence. More than 30 m of emergence has occurred in the northwest, but the extreme southern part of the region is undergoing submergence.

North American Deglacial Marine- and Lake-Limit Surfaces*

“…It is, therefore, tentatively accepted here. The zero isoline is placed offshore from southern and southeastern Newfoundland, in contrast to earlier renditions, because postglacial raised shorelines have been reported throughout that region (Brookes, 1977: 9 m at Wreckhouse; Tucker et al, 1982: 6 m at Fortune; Rogerson and Tucker, 1972: 11 m at Spear Island;Catto et al, 2000: 6 m at Horse Cove). It is far offshore from northeastern Newfoundland to Hudson Strait, as required by the high marine limits along the Labrador coast, which however decline to 15 m in the north (Løken, 1962;Ives, 1963).…”

Les plates-formes littorales de l’île aux Coudres, moyen estuaire du Saint-Laurent, Québec

“…D'une part, on y observe des marques d'abrasion glaciaire (DIONNE, 1970, p. 122;AL-LARD, 1981); d'autre part, des dépôts glaciaires ou glaciomarins recouvrent la plate-forme à plusieurs endroits (LASALLE, 1972 (GRANT, 1981 ;TUCKER et al, 1982), à Mingan (DIONNE et DUBOIS, 1979), mais pas en Gaspésie. Par contre, l'étude morphométrique des plates-formes rocheuses de la Gaspésie, entre Rivière-à-Claude et Cap-des-Rosiers, a mis en évidence la situation d'équilibre entre le nivellement des surfaces et les conditions océanographiques régionales (TRENHAILE, 1978) tandis qu'un modèle mathématique (TRENHAILE et LAYZELL, 1980) laisse supposer que ces platesformes aient pu se développer très récemment, sans qu'il y ait eu d'aplanissements anciens.…”