Although marsh foraminiferal zonations are comparatively well known for most of Atlantic Canada, data from the vertically expanded marsh zones in the Bay of Fundy are insufficient for marsh foraminiferal zonations that can be used to accurately determine former sea levels. In this paper we present data from two well-documented surface transects that illustrate vertical ranges of marsh foraminifera in the Bay of Fundy. Trochammina inflata characterizes the highest margin with a zone la of 20cm vertical range. Tiphotrocha comprimata together with T. inflata comprise zone lb (vertical range 75cm) while Miliammina fusca and other low marsh species characterize zone II faunas (vertical range 450cm). As in Atlantic marshes the fauna nearest the higher high water level produces the best accuracy for relocating former sea levels while low marsh (zone II) is not a good indicator.
Using marsh foraminiferal zonations and the tidal amplicication curve developed in earlier work, it is now possible to accurately determine former sea levels in the Bay of Fundy, at least for the last 4000 years.
RESUME
Meme si L’on connait assez bien la zonation des foraminiferes de marais pour la plus grande partie de la cote atlantique du Canada, le manque de donnees sur le development vertical des zones de marais nous empeche d'etablir avec exactitude les niveaux marins passes. Dans cet article, nous presentons des donnees provenant de deux traverses bien documentees, qui illustrent les etendues verticales des fora-miniferes de marais dans la Baie de Fundy. Trochammlna inflata characterise la limite superieure par une zone la d'une etendue verticale de 20cm. Tiphotrocha comprimata ainsi que T. inflata embrassent la zone lb (etendue verticale de 75cm) cependant que Miliammina fusca et d'autres especes de basmarais characterisent les faunes de la zone II (fitendue verticale de 450cm). Comme dans les marais at I antiques, la faune ia plus pres du plus haut niveau de maree haute procure la meilleure exactitude pour situer les niveaux marins anterieurs alors que la zone de bas-marais (zone II) n'est pas un bon indice.
L'utilization des zonations de foraminiferes de marais et de la courbe d'amplification de maree developpee lors de travaux anterieurs permet done de determiner avec exactitude, a tout le moins pour les derniers 4000 ans, les niveaux marins passes dans le Baie de Fundy.
[Traduit par le journal]
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