Deglacial history of the Champlain Sea basin and implications for urbanization

Abstract

The Champlain Sea was an inland arm of the Atlantic Ocean that inundated the St. Lawrence Lowland following retreat of the Laurentide Ice Sheet. The fine-grained sediments deposited in this sea have important implications for urbanization (e.g. slope stability, foundation design, seismic hazard assessment) of the National Capital Region. This two-day field trip reviews aspects of the deglacial landforms and deposits of the area, the Champlain Sea deposits, and reviews the societal implications from the perspectives of hydrogeology and natural hazards. On day one, a visit to the Vars-Winchester esker and environs provides the setting for discussing eskers and Champlain Sea deposits and the importance of these features with respect to regional hydrogeological issues. On day two, the focus shifts to natural hazards, with visits to a cluster of earth-flow scars at Breckenridge, Quebec, and an earth flow near Notre-Dame-de-la-Salette, Quebec, that was triggered by an earthquake on June 23, 2010. Discussion will focus on the seismicity of the earthquake and issues of seismic amplification due to variations in local geology.