A technique for analysing land-forms that is based on a theory of how particular land-forms develop over time as a result of geomorphological processes. Thus, the appearance (i.e. shape) of a landscape changes over time and this fact can be used to determine its past and future appearance. The technique was pioneered by W. M. Davis (see davisian cycle), but was introduced by Charles Darwin, in his study of the development of atolls, fringing reefs, and barrier reefs.