Creation of Colour-Contour Image using Surfer 7


Input data are Br analyses (INAA) of lake sediment samples from Central Baffin Island (GSC Open File 3176), converted to percentiles in MS-Excel

Disposition of data points

Excel file containing coordinates and Br percentile values

Step 1: Surfer is started and the “Grid” option selected

Step 2: The input file is selected. Surfer 7 will read files in Excel 2000; for earlier versions of Surfer, file should be saved in Excel 3.0 or earlier (or ASCII)

Step 3: The easting, northing and variable to be gridded and contoured are selected in the “Data” tab

Step 4: In the “General” tab, the weighting method is selected (in this case, inverse distance to a power). The “Options” field is clicked on to select weighting method (next step).

Step 5: In the “General” tab, the power of the inverse distance is selected (in this case, 2)

Step 6: In the “Search” tab, the search radius is selected. Surfer has supplied a suggestion of 193 km; this will be tried as a first attempt.

Step 7: In the “General” tab, the name of the gridded file is changed (default is the name of the input file, with extension “.GRD”)

Step 8: The name of the gridded file is selected . Clicking on “OK” will cause the gridded file to be created

Step 9: The “Map à Contour Map à New Contour Map” is selected

Step 10: The input gridded file is selected and contouring parameters are selected.

Step 11: By default, Surfer provides a grey-scale for the contoured image. Each of the grey rectangles can be customized to a specified colour and pattern by double-clicking on it (see Step 12).

Step 12: Colour can be customized by double-clicking on the ringed box

Step 13: The colour-customizing dialog box

Step 14: As an alternative, a custom-created colour scale can be saved and reloaded again and again (using ringed “Load” box in Step 11). The file is called “pc.lvl”

Step 15: Part of the graduated colour scale in “pc.lvl”. Clicking on the “OK” box will cause the colour-contour image to be created.

Step 16: Colour-contour image based on a search radius of 193 km (the internally-generated “suggestion). Clearly this radius is too great as the contouring extends into areas where there were no samples.

Colour-contour image based on a search radius of 25 km, and inverse-square (power of 2) weighting.

Colour-contour image based on a search radius of 25 km, and kriging weighting.

Colour-contour image based on a search radius of 25 km, and inverse (power of 1) weighting.


Go to Directory Page