ABSTRACT
What is a geomorphic system? Process geomorphologists commonly adopt a systems approach to their subject. To illustrate what this approach entails, take the example of a hillslope system. A hillslope extends from an interfluve crest, along a valley side, to a sloping valley floor. It is a system insofar as it consists of things (rock waste, organic matter, and so forth) arranged in a particular way. The arrangement is seemingly meaningful, rather than haphazard, because it is explicable in terms of physical processes (Figure 2.1). The ‘things’ of which a hillslope is composed may be described by such variables as particle size, soil moisture content, vegetation cover, and slope angle. These variables, and many others, interact to form a regular and
connected whole: a hillslope, and the mantle of debris on it, records a propensity towards reciprocal adjustment among a complex set of variables. The complex set of variables includes rock type, which influences weathering rates, the geotechnical properties of the soil, and rates of infiltration; climate, which influences slope hydrology and so the routing of water over and through the hillslope mantle; tectonic activity, which may alter baselevel; and the geometry of the hillslope, which, acting mainly through slope angle and distance from the divide, influences the rates of processes such as landsliding, creep, solifluction (see p. 168), and wash. Change in any of the variables will tend to cause a readjustment of hillslope form and process.
