Postglacial water-level changes of a small lake in southern Québec, Canada

• Published in: The Holocene
• Main Authors: Lavoie, Martin, Richard, Pierre J.H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: SAGE Publications 2000
• Subjects: Paleontology; Earth-Surface Processes; Ecology; Archeology; Global and Planetary Change; Subarctic
• Online Access: http://dx.doi.org/10.1191/095968300672141865; http://journals.sagepub.com/doi/pdf/10.1191/095968300672141865

Sediment stratigraphy and palaeobotanical data from five cores were used to reconstruct the postglacial water-level changes of a small lake in southern Québec. The cores were taken along two transects from the centre of the lake to the margins. Lake level was relatively high before 11 000 cal. BP, when sedimen tation was characterized by the deposition of silty gyttja (.13 000 cal. BP) and marl (13 000–11 000 cal. BP). From 11 000 to 7000 cal. BP, a sediment hiatus was indicated by the lack of two regional pollen zones between the marl and the overlying gyttja, suggesting either nondeposition or erosion of the previously deposited sedi ments due to a low lake level. The lake level was approximately 2 m lower than present on the basis of macrofossil assemblages. A rise in the water level of about 1 m occurred around 7000 cal. BP, which was interrupted by a second lowering between 6100 and 4400 cal. BP, as indicated by a hiatus in the pollen stratigra phy. During this low period, the water level was at least 2 m lower than present. The last 4400 years are characterized by a continuous rise. The lake-level fluctuations are broadly synchronous with other palaeo hydrological records in northeastern United States, Ontario, and Subarctic Québec, implying broad-scale climatic control.