When you create a contour map in Surfer and fill the contours with a colormap, the colormap is applied between the z minimum and z maximum values of the grid file, so it's likely that a specific color in one map is not associated with the same value that that color represents in the other map. This is easy to fix though. To change the colormaps so they're using the same numeric ranges:
- Select one contours layer in the Contents window.
- On the Levels page in the Properties window, make note of the Data range at the top.
- Select the other contours layer in the Contents window.
- In the Filled Contours section, click the ... button in the Fill Colors field.
- In the Colormap dialog, type the smaller of the two data minimums (from steps 2 and 4) into the Minimum box, and type the larger of the two data maximums (from steps 2 and 4) into the Maximum box.
- Click OK.
- Select the first contours layer in the Contents window.
- Click on the Levels tab in the Property Manager and repeat steps 5 and 6, using the same Minimum and Maximum values you entered for the other contours layer.
Updated October 25, 2018