TY - JOUR
T1 - Record of coupled hillslope and channel response to Pleistocene erosion and deposition in a sandstone headwater valley, central Pennsylvania
AU - Del Vecchio, Joanmarie
AU - DiBiase, Roman A.
AU - Denn, Alison R.
AU - Bierman, Paul R.
AU - Caffee, M. W.
AU - Zimmerman, Susan R.
N1 - Funding Information:
We thank S. Granke, C. Martin, and P. Silverhart for field and geographic information system (GIS) assistance, and S.L. Brantley, D.J. Merritts, and F.J. Pazzaglia for thoughtful discussion. J. Marshall and F.J. Pazzaglia provided constructive reviews that helped improve the paper. This work was supported by the National Science Foundation Critical Zone Observatories program (grant EAR-13-31726) and a Marie Morisawa Research Award to J. Del Vecchio through the Quaternary Geology and Geomorphology Division of the Geological Society of America. Field work was conducted in Rothrock State Forest, which is funded and managed by the Pennsylvania Department of Conservation and Natural Resources, Bureau of Forestry. PRIME Laboratory and M.W. Caffee acknowledge support from the National Science Foundation (EAR-1153689). Lidar data acquisition and processing were completed by the National Center for Airborne Laser Mapping (NCALM), funded by the National Science Foundation Award EAR-0922307, and coordinated by Q. Guo for the Susquehanna Shale Hills Critical Zone Observatory funded by the National Science Foundation Award EAR-0725019 (https:// doi.org /10.5069 /G9VM496T).
Publisher Copyright:
© 2018 Geological Society of America.
PY - 2018/11/1
Y1 - 2018/11/1
N2 - We sought to understand the time scale, mechanisms, and extent of landscape modification in unglaciated central Pennsylvania by studying sediment moving through and stored in a sandstone headwater valley. In this landscape, the timing and extent of landscape modification are poorly constrained, and it is unclear whether, and how much, periglacial processes drive landscape evolution during cold glacial periods. Our investigation pairs geomorphic mapping with in situ cosmogenic 10Be and 26Al measurements of surface material and buried clasts to estimate the residence time and depositional history of colluvium within Garner Run, a 1 km2 headwater valley in the central Appalachian Mountains containing relict Pleistocene periglacial features, including solifluction lobes, boulder fields, and thick colluvial toe-slope deposits. The preservation of periglacial landforms into the present interglacial suggests active hillslope sediment transport in cold climates followed by only limited modification in the Holocene. The 10Be concentrations of stream sediment and hillslope regolith indicate slow erosion rates (6.6 ± 0.6 m m.y.-1) over the past ~100 k.y. From 26Al/10Be burial dating of valley-bottom deposits recovered from a 9 m drill core, we infer two pulses of deposition since 340 ± 80 ka, a record that spans at least three glacial terminations and implies limited removal of valley-bottom deposits during interglacial periods. The age of valleybottom sediment is consistent with independent calculations determined from valley-fill volume estimates, total hillslope contributing area, and the catchment-average erosion rate integrated over multiple climate cycles. We conclude that outside of the Last Glacial Maximum ice margin, landscapes in the central Valley and Ridge physiographic province of eastern North America have experienced extensive periglacial landscape modification. Our study suggests that sandstone headwater valleys preserve soils and thick colluvial deposits that present opportunities for direct examination of the rates and dates of climatemodulated hillslope processes.
AB - We sought to understand the time scale, mechanisms, and extent of landscape modification in unglaciated central Pennsylvania by studying sediment moving through and stored in a sandstone headwater valley. In this landscape, the timing and extent of landscape modification are poorly constrained, and it is unclear whether, and how much, periglacial processes drive landscape evolution during cold glacial periods. Our investigation pairs geomorphic mapping with in situ cosmogenic 10Be and 26Al measurements of surface material and buried clasts to estimate the residence time and depositional history of colluvium within Garner Run, a 1 km2 headwater valley in the central Appalachian Mountains containing relict Pleistocene periglacial features, including solifluction lobes, boulder fields, and thick colluvial toe-slope deposits. The preservation of periglacial landforms into the present interglacial suggests active hillslope sediment transport in cold climates followed by only limited modification in the Holocene. The 10Be concentrations of stream sediment and hillslope regolith indicate slow erosion rates (6.6 ± 0.6 m m.y.-1) over the past ~100 k.y. From 26Al/10Be burial dating of valley-bottom deposits recovered from a 9 m drill core, we infer two pulses of deposition since 340 ± 80 ka, a record that spans at least three glacial terminations and implies limited removal of valley-bottom deposits during interglacial periods. The age of valleybottom sediment is consistent with independent calculations determined from valley-fill volume estimates, total hillslope contributing area, and the catchment-average erosion rate integrated over multiple climate cycles. We conclude that outside of the Last Glacial Maximum ice margin, landscapes in the central Valley and Ridge physiographic province of eastern North America have experienced extensive periglacial landscape modification. Our study suggests that sandstone headwater valleys preserve soils and thick colluvial deposits that present opportunities for direct examination of the rates and dates of climatemodulated hillslope processes.
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U2 - 10.1130/B31912.1
DO - 10.1130/B31912.1
M3 - Article
AN - SCOPUS:85055168876
VL - 130
SP - 1903
EP - 1917
JO - Bulletin of the Geological Society of America
JF - Bulletin of the Geological Society of America
SN - 0016-7606
IS - 11-12
ER -