In recent years, quantitative geomorphologists have carried out a great deal of research into the nature of fluvial processes and their effects on the natural landscape. Drainage basins have been studied as basic geomorphic units within the landscape (Chorley 1969B), and many of their properties have been determined through the techniques of morphometric analysis (Strahler 1964). Despite these efforts, little information has come to light which provides quantitative evidence of the way in which drainage basins have evolved through time.