Distinctions between cause and effect in landform development depend on the span of time involved and the size of the geomorphic system under consideration. Depending upon the temporal and areal frame of reference, variables such as channel morphology may be either dependent or independent. In terms of geologic time, landforms represent a stage in an erosion cycle and are dependent on time. On a short-term basis, components of geomorphic systems may be regarded as systems in dynamic equilibrium or in a steady state and are independent of time.