Geomorphology

Author: Diane Rowland, Center for Environmental Sciences and Education, Northern Arizona University

Coral Pink Sand Dunes State Park in southwestern Utah. The unusual ecosystem in this valley contains both old-growth ponderosa pine forest and Sahara-like dune sand. Photo © 1999 by Ray Wheeler.

Geomorphology is the study of the forms of the Earth's surface and of the processes that mold them. More recent geologic features - sand dunes, rivers, soils, lake basins, and alluvial fans, to name a few - are in most cases still undergoing formational processes. The response of these features to recent changes in climate and land use makes geomorphology an important tool for understanding our changing global climate and the effects of our increasingly intensive use of the landscape.

There are three main aspects to geomorphic study.

1. Morphologic analyses help to classify landforms; an example would be the identification of sand dune type as barchan, longitudinal, parabolic, or star.  Another example would be the classification of stream types as braided, straight, or meandering.
2. Process geomorphology involves an understanding of the driving and resisting forces behind the processes observed. In the case of sand dune, star dunes would indicate a limited sand source and multi-directional winds. In the case of streams, large meander bends indicate high sediment load and a gentle gradient. Driving forces could include changes in climate, changes in tectonic activity, and changes in land use, to name a few. Resisting forces include the geologic framework.
3. Chronological geomorphology seeks to resolve the age and rate of formation of the features. Some landforms may be characterized by their lack of change; during these periods of quiesence, soils may develop which record a myriad of both biotic and abiotic information.

The Colorado Plateau abounds in unusual geomorphic features including the tight meander bends of the San Juan River Goosenecks, the spectacular sand dunes on the Navajo Reservation, and the beautiful erosional topography of the Grand Canyon.

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