Text

theses

Shifts in temperature, precipitation, and tectonic uplift have impacted the Northeastern USA since glacial retreat, resulting in changes in regional gradient, vegetation, water budget, sediment grain size and flux to river systems. Along the northern Delaware River in Pennsylvania and New Jersey, the T2 terrace, located 6-9 m above the modern river, records most of the last 21 ka. This study elucidates the depositional history and associated temporal framework of the T2 and adjacent landforms at a locality on the eastern (New Jersey) bank of the river at 41°10'3"N, 74°53'39"W. Ground-penetrating radar (GPR) facies and bounding surfaces, descriptions of six Geoprobe© sediment cores, and basic geochemical analyses are used to characterize the alluvial architecture of the T2. The landform is comprised of five units of varying sedimentary composition, radar facies, and degree of soil formation, separated by four bounding surfaces identified by radar terminations, changes in grain size, or buried soils. A grid of GPR profiles shows unit thickness, distribution, and geometry, but channel versus overbank grain size is difficult to distinguish, and smaller-scale deposits cannot be resolved. Seven cores from the primary study site, and one core each from the T2 landform at another site and from an eolian landform nearby, are interpreted in terms of radiocarbon ages and approximate optically-stimulated luminescence (OSL) ages and the published record of the paleoclimatic, paleoenvironmental, isostatic, and anthropogenic factors impacting the valley. Incision of Units 1 and 1a (deposited as proglacial braidplain sediments) began before 14.8 +/- 0.8 ka, and seasonally-stratified lakes formed on the surface of Unit 1. Later climatic amelioration allowed the accumulation of traction sands to floodplain fines in Units 2, 3, and 4, with the most widespread unconformity and buried soil associated with the solar insolation maximum around 9 ka. Warm events (Medieval Climate Anomaly, Holocene Hypsithermal) and significant anthropogenic disturbance are associated with channel destabilization, which foreshadow the effects of future anthropogenic climate change. Finally, this study contributes to a growing body of literature that shows climate change is the dominant driving force behind changes in fluvial deposition and terracing.

ETD_4601

Ph.D.

Includes bibliographical references

by Kelsey S. Bitting

http://hdl.rutgers.edu/1782.1/rucore10001600001.ETD.000068822

doi:10.7282/T3Z31X7H

ETD doctoral

The author owns the copyright to this work.