ABSTRACT
Analysis of the morphology of weathered surfaces has used a variety of techniques. Trudgill et al. (1989, 2001) used a micro-erosion meter to measure changes in the height of points on a surface relative to a reference plane. An indication of change for each surface was derived by averaging the height changes for 120 points over each time period. It was assumed that 120 points provided a satisfactory representation of the surface. Williams et al. (2000) used a laser scanner to characterize surfaces on wave-cut platforms. Their method collects tens of thousands of height points in each time period. Inkpen et al. (2000) used close-range photogrammetry to derive a photogrammetric model of rock surfaces. The number of point data on any particular set of images collected depended upon the requirements of the operator in analytical photogrammetry and the software in digital photogrammetry. Both papers assume that the surface they are trying to measure is real, but both also highlight that the techniques being used have problems, or rather limitations, in providing a ‘true’ measure of the surface. Any measurement technique carves reality up in a distinct and limited number of ways. The entity resulting from the carving of reality is not understandable outside of the context of its associated measurement technique. Linking entities between techniques implies an ability to agree on the presence of an identical carving of reality.
