ABSTRACT
The form of the land and ocean floor affects the geologic processes, erosion and sedimentation operating upon them, and affect the ecosystems that they support. The role of human beings as agents of geologic and geomorphic change is nowhere more marked than it is in urban areas. People constantly alter the landforms in urban areas, digging foundations, filling quarries with waste, levelling playing fields, building barrier mounds along highways and constructing flood defences, harbours and wharves. The vast quantities of materials brought into cities gradually raise the level of the ground, to the extent that many old buildings now have their entrances a metre or more below the modern street level. If a development contractor drills a borehole to investigate foundation conditions, the layers of material found usually show a variety of ‘made ground’, rubble, fill material, and remains of human food and other consumption, overlying any natural soil or rock. Even urban gardens and parks often have such an anthropogenic stratigraphy beneath them. The processes and forms involved in urban activity as an earth surface process are the subject of urban geomorphology. Urban geomorphology examines the geomorphic constraints on urban development and the suitability of different landforms for specific urban uses; the impacts of urban activities on earth surface processes, especially during construction; the landforms created by urbanization, including land reclamation and waste disposal; and the geomorphic consequences of the extractive industries in and around urban areas. The diversity of urban substrates is a consequence of their geomorphic history, the ways in which past environmental changes, including climatic and sea level changes have affected the form of land and the types of surface materials.
