Change and complexity
Understanding change in the physical environment has meant understanding and applying the concept of equilibrium. Equilibrium and its validity is the focus of a continuing debate amongst geomorphologists (e.g. Mayer, 1992; Welford and Thorn, 1994). Despite the disquiet with the notion, it still has a powerful hold over how physical geographers think about reality. Even where alternative concepts are offered, they often refer to equilibrium to illustrate their difference from it. Equilibrium acts as a reference point for debate, even for its opponents. Given the important position of equilibrium, it is vital to understand what it is, how it has been applied, and how it has affected how physical geographers think.