USGS Home
Contact USGS
Search USGS

Landscape Classification, Erosion Processes, and Threshold Determination

Task Objectives

The objectives of this task were to:

1. Create a descriptive and functional landscape classification scheme for the Mancos Shale region in the study area (Gunnison Gorge National Conservation Area (NCA) that incorporated geomorphic, geologic, pedologic, and biologic attributes relevant to the source, liberation, transport, and deposition of Mancos Shale-derived sediment and mineral constituents. The classification scheme was used to organize a variety of characteristics and processes so that results from several Tasks performed in the study area could be transferred to other Mancos Shale regions.
2. Quantify hillslope rill and gully erosion rates specific to Mancos Shale landscapes in the study area. Understanding the range of erosion rates provided critical information about the supply of Selenium- and salt-bearing sediments to surface waters of the fluvial system.
3. Develop erosion threshold models for a variety of Mancos Shale landscape components in the study area. These thresholds models could be used to illustrate a great sensitivity to climate and land-use change.

Highlights & Key Findings

On-site reconnaissance, photography, and erosion mapping revealed variability in the soil texture, vegetation distribution, and erosion mechanisms on hillslopes of different aspect in the Elephant Skin Wash study area. Some of these differences were possibly due to local geomorphic variability (hillslope gradient, aspect) and soil parent-material lithologic and mineralogic characteristics.

Return to top of this page | Previous Task | Next Task | Task List