Abstracts
Abstract
The southeastern coast of Cape Breton Island from Gabarus Bay to Framboise Cove has been investigated as a typical example of a drumlin coast. Landforms have been mapped from ground observations and air photographs. Time series of coastal profiles of both beaches and eroding drumlin cliffs have been measured. Nearshore sediment distribution has been mapped. An analysis has been made of wind and wave frequency and direction data.
Four coastal segments are distinguished: (1) the south coast of Gabarus Bay has rock-cored drum-11ns separated by small barrier beaches; (2) the coast around Winging Point has a relatively stable depositional tombolo coast; (3) Fourchu Bay and Framboise Cove are developed in an area of thick till drumlins, and consist of barrier bars backed by lagoons and drumlins; and (4) the Fourchu Head and Red Cape are rocky coastlines from which all till has been removed by marine erosion,
The geomorphologlcal evolution is a consequence of the initial drumlin landscape, the availability of a wide range of sediment sizes, and the type and intensity of marine erosion processes including the effects of transgression. Two types of coast are developed: a) in irregular hilly areas, where the till is thin and occurs in rock-cored drumlins; and b) in valley areas, where thick till drumlins are found. In each of these types, three stages of coastal development are distinguished. These represent the effect of differing rate of maturation, dependent on the configuration of drumlins and varying type and intensity of marine erosion.
RESUME
Depuis la baie de Gabarua jusqu'a l'anse Framboise, la cote sud-est de l'tle du Cap-Breton a ete etudiee en tant qu'exemple type d'une cote a drumlins. Les formes de relief ont ete cartographies a partlr d'observations sur le terrain et de photographies aeriennes. On a mesure a differents intervalles de temps, des series de proflis cotiers comprenant des plages alnsi que des falaises de drumlins soumlses a 1'erosion. La distribution des sediments littoraux a StS cartographlee.
On distingue quatre environnements cotiers. Le littoral sud de la bale de Gabarus est caracterise par des drumlins a noyau rocheux separes par des plages barrleres de faibles dimensions. La cote a tombolos qui entoure la pointe Winging est un envlronnement de deposition relatlvement plus Btable. Dans les regions de la baie Fourchu et de l'anse Framboise, des drumlins constitues d'un till epais sont 2 l'orlgine d'une cSte barriere appuyee par des langunes et des drumlins. Les cotes rocheuses du cap Fourchu et de Red Cape ont ete denudfies de leur till par 1'action erosive de la ner.
L'evolution geomorphologique de la cote ressort du paysage a drumlins original, de la disponibi-litS d'une vaste gamme de sediments, ainsi que du type et de l'intensite des processus drerosion marine, y compris les effets de la transgression. On reconnect deux types de cotes: l'une aar-acterisee par un paysage seme de collines oiil'on retrouve un till mince associe & des drumlins 2 noyau rocheux; 1'autre, que l'on retrouve dans les vallees, se distingue par d'epais drumlins constitues de till. Chacun de ces types de cotes se developpe en trois Stapes correspondent a des regimes de maturation differents qui dependent de la configuration des drumlins ainsi que de 1'intenBite et du caractere particuller de 1'erosion marine.
[Traduit par le journal]
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