Évolution d'un milieu littoral et remontée du niveau relatif de la mer à l'Holocène supérieur au nord de l'île du Cap-Breton, Nouvelle-Ecosse

• Published in: Canadian Journal of Earth Sciences
• Main Authors: Vernal, A. de, Lortie, G., Larouche, A., Scott, D. B., Richard, P. J. H.
• Format: Article in Journal/Newspaper
• Language: French
• Published: Canadian Science Publishing 1985
• Subjects: General Earth and Planetary Sciences; Breton Island
• Online Access: http://dx.doi.org/10.1139/e85-031; http://www.nrcresearchpress.com/doi/pdf/10.1139/e85-031

The sedimentary sequence in a coastal pond on Cape Breton Island was examined by various analyses (pollen, plant macrofossils, diatoms, and rhizopods). The results allow for the reconstruction of different phases in the evolution of the pond in conjunction with relative sea-level rise during the late Holocene. Throughout the period studied the microflora and microfauna indicate that the pond was mainly freshwater, isolated from the sea by a continuous sand and gravel bar. Three phases in the pond evolution have been identified: (1) the lowermost part of the sequence is characterized by mineral detrital deposits and some marine fossils related to the reworking of bar sediment by storms and high tides washing over the rock sill; (2) this was followed by a rapid filling of the basin by organic detritus provided by shore washing processes; (3) a marsh evolving into a shallow lake completes the sequence up to the interruption by human occupation. The lake-level rise is linked to the formation of the bar, which was controlled by the highest storm-beach level. A submersion rate of 18 cm/century has been calculated using the beginning of the lacustrine phase, which was dated at 2680 years BP (UQ-616).