ABSTRACT
QUALITATIVE THEORIES Included within this group are some of the most widely known studies of hillslope evolution. The style of these studies is exemplified by the work of Davis (1899) who proposed an evolutionary model for valley sides within his wider concept of the geographical cycle. Davis's argument may be summarised as follows (Figure 8.2):
(i) Valley sides are created by downcutting streams. Initially, the rocks through which the streams have cut are exposed at the surface of these valley sides and the detail of their morphology (cliffs and ledges) reflects the character of the subjacent rock.
