Evidence for Changes in Paleoenvironments along the Lower Cap-Rouge River, Québec (Canada), in Relation to a High Water Stand during the Mid-Holocene Laurentian Transgression

Abstract

ABSTRACT Verville, J.-F.; Filion, L., and Lajeunesse, P., 2014. Evidence for changes in paleoenvironments along the lower Cap–Rouge River, Quebec (Canada), in relation to a high water stand during the mid-Holocene Laurentian transgression. At the outlet of the Cap-Rouge River, upstream of the Quebec sound on the St. Lawrence north shore, a 5-m-high stratigraphic section was excavated within an urban area, specifically, in a schoolyard located on the 14 m terrace on the east side of the river. Our stratigraphic and high-resolution macrofossil data show that major paleoenvironmental changes occurred along the lower Cap-Rouge River during the mid-Holocene. Macrofossil assemblages indicate that during a low water stand between 6320 and 6230 cal YBP, eastern hemlock (Tsuga canadensis [L.] Carr.) and white pine (Pinus strobus L.) formed mixed stands on the sandy terraces flanking the river. They also indicate that these mesophytic forests shifted to hydrophytic plant communities (eastern larch and aquatic plant...