Solifluction steps and risers, Lee Ridge, Glacier National Park, Montana, USA: a scale and pattern analysis

Solifluction patterns on Lee Ridge, Glacier National Park, Montana, USA, were characterized through a combination of field transects, enhanced, digital aircraft data, and geostatistics. The objectives were to (i) assess the role of high spatial resolution digital imagery for mapping the areal extent and spatial pattern of solifluction steps and risers through digital enhancements [i.e., principal components analysis (PCA) and wavelet transforms (WTFs)] of ADAR-5500 aircraft imagery; (ii) describe the pattern of solifluction steps and risers through the placement of twelve 50-m field transects oriented normal to the steps and risers and organized along an elevational gradient extending from highest to lowest positions along the ridge; (iii) define scale dependent relationships of the solifluction steps and risers mapped along one-dimensional field transects and two-dimensional remote sensing images using indicator semivariograms to define the structure of the spatial data across a range of sampled scales; and (iv) relate the solifluction patterns observed through the transects and the remote sensing interpretations to topographic trends associated with distance from the dominant peak, a proxy for elevation change along Lee Ridge. Findings suggest that the semivariance pattern of the transects changes with elevation, that is the semivariograms of the lower transects show smaller amplitudes and shorter wavelengths than those at higher elevations, and the pattern of steps and risers from the enhanced ADAR-5500 images indicate less variation in the semivariance with elevation than represented in the field transects.