Crustal Imaging and Characterization Team

Spectral Characterization of Piedmont Agricultural Soils and Soil Erosion in Lancaster County, Pennsylvania

Subtask Objectives

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Earth Observing-1 (EO-1) Hyperion data acquired from the same orbital swath are being used to classify soils based on clay mineralogy and clay abundances. Lancaster County is an ideal sight for such this study because the soils are plowed seasonally providing good exposures and hundreds of years of farming and soil erosion have exposed deeper, clay-rich soil horizons.

Statement of Work

Task is no longer active.

Highlights & Key Findings

The composition of soils in Lancaster County is variable and reflects changes in the underlying parent bedrock material as well as surface and ground water hydrological conditions. For example, much of the agriculture and urban expansion occurs on soils derived from Cambro-Ordovician limestones and dolomites high in insoluble residue content. Other bedrock types include deeply weathered quartzites, chlorite- and sericite- schists and gneisses. Therefore, clay minerals in soils can be used as proxy for mapping compositional changes in poorly exposed bedrock, and as tracers for identifying upland sediment sources, including legacy sediments stored along the stream banks.

Calibrated ASTER VNIR-SWIR (0.56 - 2.40 microns) reflectance spectra and spectral unmixing methods were used to map soils containing variable amounts of chlorite, smectite, kaolinite, illite or muscovite. So far field samples, mostly from the northern portion of the Little Conestoga tributary watershed, confirm the presence of abundant smectite in the soils which was not previously reported in the National Resources Conservation Services' soil characterization database. EO- 1 Hyperion spectra agree with ASTER and the former was used to distinguish between chlorite and calcite, as well as discriminate between soils containing kaolinite, smectite and illite-muscovite which were inseparable using the ASTER data. The southern portion of the Little Conestoga tributary watershed is dominated by chloritic soils. Legacy sediments trapped behind a downstream 18th century mill dam is currently being cored and will be analyzed for chlorite. These sediments are silty-clay loam deposits, and if derived from upland soil erosion, should reflect the inverse of clay compositions found in a typical soil profile.

Return to top of this page | Task List | Main Task | Next Subtask

Accessibility FOIA Privacy Policies and Notices

U.S. Department of the Interior | U.S. Geological Survey
URL: http://crustal.usgs.gov
Page Contact Information: CICT Webmaster
Page Last Modified: