Comparison of Air Photo Landform Units to Statistically Defined Groups of Tors in Dartmoor, Southwest England.

摘要

Landform mapping units delineated using manual photo analysis procedures on two air photo mosaics, one at a scale of 1:24,000 and the other at 1:50,000, were compared to groups of tors defined using multivariate statistical analysis of field and laboratory data. Correspondence between the results of the two procedures was quite good: (1) members of most tor groups occur in the same landform mapping unit; (2) most landform mapping units contain far greater proportions of one, or not more than two, tor groups; and (3) the tor types defined statistically as typical of a given landform mapping unit tend to agree with the actual distribution of tor types in that mapping unit. The landform mapping units can thus be defined in terms of statistically significant descriptors in addition to descriptors based on analysis of stereo air photos. Finally, the greater number of mapping units on the 1:50,000 scale photo mosaic combined with the fact that most of the landform units were associated with one, rather than two, tor groups and with the greater similarity between statistically defined tor types and the actual distribution, suggests that smaller scale photos may be more useful than larger scale photos in relating photo-derived landform patterns to groups of tors defined statistically using field and laboratory data. Air photo analysis, landforms, granite, multivariate statistics.