11 - Factors of soil formation: topography

Summary

The term topography refers to the configuration of the land's surface. The topography of an area incorporates its relief (relative differences in elevation), its aspect (position with respect to compass coordinates), and the general shape and connectivity of land surfaces. These attributes mediate how external factors, such as solar radiation, precipitation and wind, impinge upon a site. Topographic relief imparts potential energy, by virtue of gravity, that functions to move water and regolith from higher landscape positions to lower ones. The movement of materials, including water and soil materials, on a landscape is influenced by the slope gradient and shape and the degree of connectivity of drainage networks. Thus, from a pedologic perspective, topography is important because it exerts a strong influence on the disposition of energy and matter experienced by soils on the landscape.

The processes that create topography are usually geologic in nature; e.g. tectonic uplift, fluvial erosion and deposition, mass wasting, volcanic activity and glaciation. A landscape produced by these processes is the blank canvas upon which soil patterns are painted by processes that are linked to topography. As time passes, these processes leave characteristic pedogenic imprints on different parts of the landscape, altering the original parent materials and differentiating the physical, chemical and biological nature of the soils by topographic position.

Topographic elements of landscapes

In most landscapes, topography governs the movement of water and is shaped by it.