Automatic identification of topographic surfaces related to the sub-Cambrian peneplain (SCP) in southern Norway — Surface generation algorithms and implications

Two methods for digital mapping and analysis of topographic surfaces of moderate relief, such as erosional surfaces, are introduced and discussed in this paper. The surface fit method uses least squares to solve the problem of finding the best surface fit to the data, whereas the region grow method uses the surface slope and a set of properties (e.g. maximum slope between adjacent pixels) to generate surfaces from single seed GPS-positions. In both methods the analysed surface was identified from field controlled geological maps. The surface fit method is applicable to landscapes with great topographic varieties, whereas the region grow method is most applicable to relatively flat areas. Both methods were used to identify the sub-Cambrian peneplain (SCP). The result suggests that the SCP occurs across significant parts of the Hardangervidda area, with a greater lateral extent in the central part of the area compared to the northern part. This can be attributed to more extensive faulting of the SCP in the northern part.