The drift thickness and structure contour of the bedrock surface maps were determined from bedrock stratigraphic picks made from three main sources: oil and gas wells, water wells and surficial geology maps. In oil and gas wells, the bedrock picks were made using geophysical logs with additional information from drill cuttings. From water wells, lithologic descriptions were used to determine the depth to bedrock pick. Surficial geology maps were used to obtain bedrock outcrop locations and areas of thin drift (less than 2 metres) overlying bedrock. Tabulated data of bedrock picks and GIS polygons of thin drift were imported into ArcGIS v9.0 for computer contouring on a desktop computer. Ground surface elevations were imported as DEM data into the project software. Bedrock depth picks of each data point were then converted to bedrock elevations above sea level by subtracting depths from DEM data values at that data location. The data were then gridded using the Natural Neighbors method in the 3D Analyst tool in ArcGIS. The resultant grid of the bedrock surface was checked for conflicts and edited to not exceed the ground surface. Next the corrected grid was contoured using XTools in ArcGIS. The contoured lines were then manually edited using the ArcGIS software to reflect a valley incision geological model. The final bedrock contours were regridded using a 60 m cell size to produce infill colour rendition. The drift thickness map was finally created by subtracting the bedrock surface grid from a grid of the ground surface topography. The resultant grid was then smoothed using Neighborhood Statistics under the Spatial Analyst tool in ArcGIS using the following parameters: rectangular mean statistics type, neighbourhood settings of cell height and width of 7, and output cell size of 100. The resultant grid was then contoured to create a drift thickness map.

All map interpretation and preparation was done using ArcGIS v9.0 on a desktop computer.