Very precise measurements of the movement of coarse-textured, unconsolidated materials may be meaningless. Therefore the study of individual processes operating on footpaths may require a different approach. However, for identification of changes of reasonable dimensions, methods such as those described above are inexpensive, quick, and require no technical expertise. It may be argued that, for path management, erosion that is too limited to be measured by these methods is too limited to be a problem. It can certainly be argued that the problem of spatial correlation implies a large number of measurements. What is lost in lack of precision may be more than compensated for by the gain in data from the larger area and wider variation in site-types that it is possible to monitor with such simple techniques.

To monitor the effects of recreation in mountain areas, it is desirable to be able to measure any change in path-state and relate this to recreation factors at different seasons and under different sit; -conditions. Three methods of measurement have been considered in this paper, corresponding to three time-scales. Aerial photography has been used to demonstrate trends over the long term, and has proved adequate to differentiate between path sections with differing resistance to erosion.

Short-term measurement has been carried out relative to known fixed positions. Two methods are suggested. One is less precise, but simple and widely applicable, and can be used for measurement intervals of six months to one year. The other is more detailed and can be used for measurement intervals of a few days, but is limited in its application by practical considerations.

It is suggested that simple techniques used at a large number of different types of site may be more effective than detailed measurements at a few sites.