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 mineral exploration drillholes. In oil and gas wells, the bedrock picks were made using geophysical logs. From water wells and mineral drillholes, lithologic decriptions were used to determine the depth to bedrock pick. Picks data were tabulated and imported into a contour-mapping software (MacCad v6.0) using a Macintosh desktop computer. The data were then gridded by triangulation using the Delaunay tuple method. The resultant grid was then contoured using the mapping software. The contour lines were then manually edited on the computer using the MacCad software. The final line interpretation was then gridded again using 400 x 400 grid matrix to produce infill colour rendition.
Final map preparation was as follows: the bedrock contour and gridded data were exported from MacCad in .dxf format and imported into ArcInfo v8.3. The attributes were deleted. The coverages were transformed from page units to real world coordinates (RMS error +/- 20 m) and projected to UTM12 NAD83. The contour lines were smoothed, tagged with the corresponding elevation values and exported to shapefiles. Map compilation was done using ArcGis v8.3.