Regional geoscience information : Ottawa-Hull

Initiated in 1970, the project to supply geoscience information for the Ottawa-Hull area provides both background data on geological conditions and reference material for regional planning. Precambrian igneous and metamorphic rocks outcrop to the north and on the up thrown side of major faults, as well as form the basement of the area. Flat to nearly flat-lying limestone, sandstone, dolomite, and shale of Paleozoic age overlie the Precambrian rocks in most of the study area. Glacial deposits of till and sand and gravel have been modified extensively by wave action or have been buried under thick marine clays during inundation of the area by the Champlain Sea. During and fallowing emergence of the land from the sea, the present river channels were cut and older channels were abandoned resulting in the formation of numerous scarps. Data on bedrock geology and geotechnical characteristics of the bedrock were compiled on two maps included in this report. The presence of major fault s, jointing, and the easily erodable nature and the sulphureous water content of some shales all influence regional planning . The map of surficial materials and terrain features reveals the area to be complex with the predominant depositional unit, from the urban planning point of view, being Champlain Sea clays. Borehole and seismic data form a data bank from which bedrock topography and drift thickness trend maps have been produced by computer. Bedrock topography maps reveal a deep buried channel beneath the present course of Ottawa River downstream from Chaudiere Falls and a bedrock valley underlying the present course of Rideau River . Drift is up to 240 feet (75 m) thick along the course of the Ottawa River buried channel; thicknesses over 100 feet (30 m) are not uncommon east of Ottawa and along the north side of Ottawa River in the Quyon map area. The data presented are primarily for the purpose of demonstrating the utility of geoscience information. Urban areas are urged to gather, analyze , and use more geoscience information in regional planning .