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U.S. DEPARTMENT OF THE INTERIOR

BUREAU OF LAND MANAGEMENT

Oregon / Washington

Soils

Soils
Stream entrenchment showing soil structure and juniper roots in central Oregon.

Soils form an ecologically rich and active zone at the interface between geologic materials and the atmosphere.

The soil that occurs at a particular site depends on the geologic parent material, climate, relief, vegetation and organisms occurring at the site. Given the amount of time that has been available for these soil-forming factors to interact, different soil properties will develop.

In general, forested environments have thicker and more continuous organic matter layers consisting of duff material above the mineral soil compared to rangeland soil horizons. The thickness and amount of organic material varies considerably depending on local vegetation characteristics, climate, relief, and disturbance history (including human uses and fire).

The BLM addresses the health and productivity of soils and evaluates the potential impacts of projects to soils when they prepare resource management plans and subsequent environmental impact statements and environmental assessments.

Geologic Interpretation of Floodplain Deposits of the Southwestern Willamette Valley Study

The BLM owns and manages 2,200 acres of land in West Eugene and participates as a partner in the West Eugene Wetlands program along with other local and federal agencies. Interpretation of soils and landforms is part of the BLM Soil Scientist's responsibility and is integral to the success of restoration of wetlands and adjacent uplands. This initial study, with the cooperation of many scientists and the University of Oregon, resulted in a surprising find which redefined the origin of the surficial gray clay in the Willamette Valley as being from the Mt. Mazama volcanic eruption, over 7700 years ago. Research and refinement of the characterization of this stratigraphic unit continues and supports the significance of this discovery.