Landscape memory: the imprint of the past on contemporary landscape forms and processes

The imprint of the past upon contemporary landscape forms and processes is differentiated in terms of geologic, climatic and anthropogenic memory. Geologic memory refers to controls exerted upon relief, erodibility, erosivity and accommodation space (areas in landscapes where sediments are stored and reworked). These factors set the imposed boundary conditions within which contemporary landscape-forming processes operate. Climatic memory refers to the influence of past climatic conditions upon contemporary landscape forms and processes. Climatic controls exert a primary influence upon the nature of geomorphic processes, while the influence of climate upon ground cover affects the effectiveness of these processes. Climate change may induce profound alterations to the flux boundary conditions under which contemporary landscapes operate. This is exemplified by the variable imprint of glacial/interglacial cycles in differing parts of the world. Anthropogenic memory refers to the imprint of past human activities on contemporary landscapes, whereby human disturbance in the past altered landscape forms, processes and associated flow/sediment fluxes in a manner that continues to affect the way the contemporary landscape works. Contrasting examples from a tectonically stable landscape (Australia) and a tectonically uplifting landscape (New Zealand) are used to highlight the variable influence of geologic, climatic and anthropogenic memory upon the persistence and erasure of landscape forms and resulting implications for sediment flux in differing settings.