CGRG Bibliography of Canadian Geomorphology
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Author : Berube, D.; et Olsen, L.
Date : 2001.
Title : Geomorphological evolution of Grande Plaine, Miscou Island, northeast coast of New Brunswick.
Publication : Coastal Science and Engineering, challenge for the new Millennium. 2001 Canadian Coastal Conference. May 16-19 2001. Universite Laval. Pavillon La Laurentienne, Quebec, QC.
Issue :
Page(s) :
Abstract
Miscou Island is located on the northeastern coast of New Brunswick, at the mouth of Chaleurs Bay. Forming the terminal end of a shore drift cell, the northwest coast of the island is characterized by a series of approximately 30 parallel beach ridges. This uncommon coastal landform, called Grande Plaine by the people of the island, extends for 5.5 km and reaches a maximum width of 1.2 km. Over the last decades, many camping sites and cottage clusters have been developed on this plain, without taking into account the dynamic nature and vulnerability of sand ridges. In fact, what do we know about the short and long term evolution of Grande Plaine? The first detailed description of Grande Plaine was published in 1906, in the Bulletin of the Natural History Society of New Brunswick. The author, W.F. Ganong, underlines that the mode of formation of the plain involves an interesting anomaly, that is the progradation of a shoreline on a submerging coast. Unfortunately, this naturalist, endowed with a good sense of observation, did not have the tools to fully assess the extent of this phenomenon, and nobody after Ganong has really paid attention to the site. This is why the Geological Surveys Branch, of New Brunswick Department of Natural Resources and Energy, has initiated last year (2000) a research project on the geomorphological evolution of Grande Plaine. Firstly, a digital photogrammetry study, using CARIS-GIS program, has been conducted to assess the variations in the position of the coastline between 1944 and 1996. The superimposition of rectified air photos has revealed that the coastline advances at a rate of 1-3 m/year in the southern and central parts of the plain, and retreats at a rate of 2-4 m/year in the extreme northern part of the plain. Secondly, excavation works have been carried out in order to describe the characteristics of the sand deposits. Shell fragments have been found at a depth of 0.3-0.6 m along two beach ridges, located respectively at 325 and 690 m from the actual coastline. A date (14C) has been obtained for each beach: 1900 ± 70 BP and 2060 ± 70 BP. Finally, surveying works have been carried out in order to measure the topographical variations across the plain. Preliminary results suggest that the upper limit of the backshore, along the two dated beaches, is located at an altitude of 0.5 m; which implies that the mean sea-level has risen by at least 1 m since 2000 BP. These new data on the evolution of Grande Plaine, and the data that will be collected over the next year, are essential to guide future tourism developments and ensure that the ecological integrity of this site will be preserved.
Bibliography of Canadian Geomorphology