1. Structure: refers to the nature of solid materials that form the surface and subsurface, their composition, texture, fabric, architecture, mechanical strength, and other physical attributes.

2. Process: refers to the physical, chemical, biological or human processes that shape the surface into landforms. Broadly speaking, processes are either depositional (constructive) or erosional (destructive).

3. Time: refers both to the rate at which a process modifies the surface and to the length of time or duration that a process has operated at a site.

The processes that shape landforms can be categorized as endogenetic or exogenetic. Endogenetic processes are related to plate tectonics and to the surface effects of plate movements, both horizontally and vertically, as well as to other processes originating from the Earth's interior. Exogenetic processes develop at or above the surface in the atmosphere, hydrosphere, cryosphere, or biosphere. They involve wind, water, ice, mass movements, or living organisms that modify landforms. Impact and accumulation of extra-terrestrial materials (meteorites, comets, etc.) are also exogenetic processes.

Endogenetic and exogenetic processes combine with structure and time to produce the observed landforms at the Earth's surface. Most landforms involve a considerable mass of material--bedrock and sediment, and so are slow to adapt when environmental changes take place. The geomorphology of a region, therefore, represents a long-term integration of environmental conditions and trends. A region's geomorphology is, thus, a reflection of both past and present environments.