Research Interests

• Sedimentary Processes

Current Research

• www.duke.edu/~tpg

Past Research

University of Montana
I completed an undergraduate research project examining the late Pleistocene to Holocene transition as recorded in the geochemistry of sediment cores collected in Flathead Lake, Montana. My work focused on a 7m core that spanned at least 4kyr beyond the onset of the Holocene (no 14C dates at present). I measured geochemical proxies and grain size over the entire core with facilities provided by the Murdock Geochemistry Laboratory at the University of Montana. The work constituted a preliminary data set to be included in a larger proposal to both expand work on existing cores and recover additional cores for study. The overall objective of my study was to understand how the sediments of Flathead Lake, a large proglacial lake at the margin of a continental (Cordilleran) ice sheet, recorded changes in the ice lobe at its northern boundary. In particular, the range and frequency of changes in the sedimentary record is considered to reflect the relative stability of the ice sheet during significant shifts in mass balance (and thus proglacial hydrology) associated with continental deglaciation.

NSF Research Experience for Undergraduates
The summer before arriving at Duke (2002) I spent 8 weeks in an NSF Research Experience for Undergraduates studying global climate change issues from a broad range of perspectives. My research involved the effects of extreme drought on water quality in a large watershed east of the continental divide in Colorado. A colleague (Hannah Chapin) and I measured flow and several water quality indices on a number of stream reaches within the watershed. Our particular focus was ammonia concentrations - a threat to cold-water fish species - mostly introduced by wastewater dischargers. Specifically, we compared field measurements with model based studies on permissible ammonia discharges by wastewater treatment plants used for permitting under the Clean Water Act. The punchline? Extreme weather events, predicted to increase as the planet warms, may force water quality management to reassess the assimilative capacity of surface waters, especially in the arid west.

Advisor: Lincoln Pratson