Introduction

Time pervades all fields of geomorphology, from the most restricted observation of an obscure localized geomorphological process, for example the solution of minerals from potholes in glacially eroded granites, to the macroscopic, highly abstract modelling of drainage systems development over several thousands of years. The fundamental temporal attribute of duration may be compared to the spatial qualities of area or distance in that they are of finite and of measurable magnitude. Geomorphological data may be classified on a time basis for they may possess several distinctive properties. Velocity and acceleration are vital elements of geomorphological process studies. Geomorphological phenomena may be regarded as slowly changing or dynamic, if measured against the human time scale. Moreover, some of the most important geomorphological concepts, are time-centred —— equilibrium and grade, magnitude and frequency, equifinality, denudation chronology, variance minimization and entropy maximization. The chapter also provides an overview of the key concepts discussed in this book.