HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bain, D. J. Articles by Brush, G. S. Search for Related Content Articles by Bain, D. J. Articles by Brush, G. S. GeoRef GeoRef Citation

Early chromite mining and agricultural clearance: Opportunities for the investigation of agricultural sediment dynamics in the eastern piedmont (USA)

Daniel J. Bain and Grace S. Brush

Department of Geography and Environmental Engineering, Johns Hopkins University, Baltimore, Maryland 21218

Present address: United States Geological Survey, 345 Middlefield Road, MS 420, Menlo Park, California 94025;djbain{at}usgs.gov

Many flood plains in the Eastern Piedmont (USA) are buried under deposits of sediment resulting from European agricultural clearance. Classic radioisotopic dating techniques cover temporal periods too short (¹³⁷Cs, ²¹⁰Pb) or too long (¹⁴C) to reliably date sediments deposited during periods of local European activity (1660-1900). Moreover, many potential biomarkers, such as pollen, degrade in oxic flood plain sediments. In the Baltimore, Maryland (USA) region, early chromite mining (1820 –1880) occurred during periods of rapid agricultural clearance. Use of chromium (Cr) chemostratigraphic profiles in flood plain sediments tied to historical mining activity can provide improved precision in overbank accumulation rates and timing. Sediment cores were collected from the Red Run basin, which is part of the Baltimore Ecosystem Study, an urban Long-Term Ecological Research site. Trace metal chemostratigraphic profiles were measured and peaks in Cr concentration tied to historic mining activity. Dates from Cr chemostratigraphic profiles were combined with ¹³⁷Cs dating to reconstruct flood plain sedimentation rates. Red Run early sedimentation rates (1820 –1880) were higher (0.45 –1.19 cm/yr) than more recent (1880 –1963) rates (0.08 –0.46 cm/yr). This indicates that Piedmont flood plain vertical sediment accumulation might have peaked before the peak in agricultural clearance, earlier than assumed by regional models. The Cr chemostratigraphy is applicable to a wider region including much of the Maryland and Pennsylvania (USA) Piedmont.