Geomorphology

Geomorphology is the science that studies land-forms, including their shape (morphology) and spatial distribution (location and position in the landscape), the materials of which they are composed (bedrock, soils, sediment), and the processes that form, maintain, and change them over time. Geomorphology has long been recognized as a major subfield of geography and geology, but in recent decades, concepts and techniques from geomorphology have been applied widely in engineering (e.g., restoration of damaged streams), ecology (e.g., estimating fish abundance as a function of physical habitat features), forestry (e.g., evaluating the stability of hillslopes), agriculture (e.g., modeling soil erosion), hydrology (e.g., assessing flood hazards, finding groundwater), archaeology (e.g., reconstructing past environments), pedology (e.g., explaining the movement of heavy metals, relative age dating of geomorphic surfaces using soils), space science (e.g., landforms on Mars), and environmental planning (e.g., evaluation of geomorphic hazards such as dust storms, coastal erosion). Many opportunities exist in geomorphology to share concepts and techniques with practitioners in other branches of physical geography (“integration”) and in human geography (“synthesis”). Geomorphology is an intimate part of the emerging, interdisciplinary field known as Earth system science, a scientific approach to describe, explain, and predict biogeochemical phenomena at or near the surface of the Earth. A significant number of geomorphologists practice Quaternary geomorphology, the reconstruction of past environments. This part of geomorphology has received new vigor in light of the need to predict the effects of climate change, a task that profits from the ability to decipher past adjustments between form and process.

On the one hand, geomorphology is a basic science in that it seeks to understand the diversity of landforms without necessarily having any direct implications for human activities. On the other hand, geomorphology is an applied science because concepts and techniques from geomorphology are applied to practical problem solving in engineering, resource evaluation, and environmental planning.

Geomorphologists study landforms on a variety of spatial scales, ranging from regional/continental (e.g., stream networks, mountain building) down to microscopic (e.g., development of soil crusts, cosmogenic dating of earth materials). A reductionist approach, which relies on principles from physics and chemistry, has proven useful in explaining small-size phenomena, for instance, in [Page 1245]understanding the factors that affect the initial movement of an individual particle by wind or water. However, for larger-size phenomena, probabilistic modeling approaches have provided more explanatory power. What is ordered and regular at one spatial or temporal scale may be disordered and irregular at another scale. Some exciting new developments in mathematical modeling in geomorphology have emerged from the application of complexity and chaos theory.

Geomorphologists rely on an amazing array of field methods for the collection of primary data, supplemented by secondary data sources: topographic maps, digital elevation models, land surveys, soil surveys, geologic maps, aerial photography, satellite imagery, and numerical dating techniques. Data are also collected in laboratory settings with physical models (e.g., wind tunnels, flumes) and lab analyses of soil and sediment samples (physical-chemical analyses, dating). Data are analyzed using geographic information systems, computer simulation models, and geospatial statistics.