Shaded Relief [PDF, 3.7 Mb, viewer]

The bedrock topography map ( Maps - GeoServ ) shows the bedrock relief as it would appear if the cover of unconsolidated deposits was removed. The continuous bedrock surface is obtained by interpolation between known values of bedrock elevation (control points). The control points come from surficial geology maps, digital topographic data, and the Geoscientific Database. The first step is to overly, in a GIS, a digital elevation model (DEM) on a surficial geology map. In areas of bedrock outcrops, the bedrock topography is taken directly from the surface topography on the DEM. In areas where the bedrock is covered by unconsolidated deposits, the bedrock elevation is taken from values provided by the Geoscience Database. The bedrock topography can be displayed using various techniques, such as shaded relief and a standard elevation contours using coloured class intervals.

The shaded relief [PDF, 3.7 Mb, viewer] bedrock topography emphasizes the contrast between the complex structure of the Precambrian formations and the horizontal bedding of the Paleozoic rocks. ( Note: numerous faults transect the Precambrian formations north of the Ottawa River, as suggested by the topography, but are not reported on the map due to the lack of precise information on the location of the faults at the regional scale. Information in this region will be updated as it becomes available.) Transition between Precambrian and Paleozoic formations is generally smooth except in areas where the contact occurs at a fault line, such as south of the Carp Ridge and south-east of the Gatineau Hills. Despite the importance of fault block displacements in the Paleozoic formations, the differential displacement between fault blocks have little influence on bedrock topography, due to the erosional levelling that took place following the Ordovician period.

The contour map shows that the bedrock elevation of Paleozoic formations generally increases from east to west, and that Precambrian formations clearly dominate the entire area. Despite the importance of fault block displacement, the topographic trend of Paleozoic formations still reflect the gradual slope of the Ottawa Embayment. Superposition of fault lines on bedrock topography shows that differences in resistance to erosion of the various Paleozoic formations and fault block displacement has little to no influence on bedrock topography.