Geomorphometrical analysis of glacial and Aeolian lineaments on satellite images
Some glacial and aeolian geomorphological features express themselves as parallel lineaments on satellite images. These landforms represent readily available evidence for reconstructing Quaternary environments, and are believed to have preserved in their morphometry, evidence of their formation. Drumlins, megatlutes, tlutes and mega-lineaments are typical examples of glacial lineaments, while linear sand dunes are examples of aeolian lineaments. The main aim of this thesis was to develop an objective method of characterising the spacing between parallel glacial and aeolian lineaments and to attempt to answer some geomorphological questions about them. The method of spectral analysis based on fourier transformation was used. Spectral analysis on radiometric transects taken perpendicular to the trend of parallel lineaments on satellite images permits the spacing between these lineaments to be assessed and thus the dominant spatial frequency to be determined. This provides a quick and efficient method of morphometric analysis. A methodology for doing this has been established and applied to examples of large scale ice moulded landforms in Canada and aeolian linear sand dunes from the Kalahari desert. Analysis of the spacings obtained showed that for the case of aeolian lineaments in the study area, there was no significant trend in spacing up or downwind indicating equilibrium in spacing in the overall dunefield. The analysis of the spatial frequency of glacial lineaments established that a significant relationship existed between lineament spatial frequencies and inferred velocities and that the behaviour of the spacing is systematic up/down ice. An important result obtained from analysing these lineaments was that the spatial distribution showed a concentration of spacing at a particular range of frequencies (150 to 750 metres) proving that the distribution of the landforms is not multimodal as has been previously hypothesised but is scale continuous.