Our group’s current research themes include: 1) Dust and loess as archives of climate and agents of climate change in both deep-time (late Paleozoic) and near-time (Quaternary-Miocene) systems; 2) investigating the hypothesis of upland glaciation in low latitudes of late Paleozoic Pangaea; and 3) silicate weathering in fluvial (river) systems, and impacts on carbon cycling. My advisees typically undertake thesis, dissertation, or post-doctoral research that involves conducting sedimentological sampling and analyses, and both field and lab work. Some projects involve scientific drilling. An example of the latter is the Deep Dust Drilling Project, which will recover one of the longest continuous sedimentary cores in the western hemisphere to interrogate climatic, tectonic, and biotic aspects of the Permian in equatorial Pangaea.
Which way did the winds blow? How dusty was the atmosphere? Did dust influence carbon cycling? Our group pioneered studies of loess(ite) and eolian-marine (wind-transported but marine-deposited) silt preserved across Pangaea to assess atmospheric dustiness, and paleoatmospheric circulation, and interrogate how dust may have fertilized ecosystems in the late Paleozoic. We're also investigating Miocene-Quaternary dusts, and the origin of silt. Dust and loess deposits are rich repositories of paleoclimate data, and inform our understanding of how dust may have influenced carbon cycling in deep time.
The late Paleozoic was Earth’s penultimate icehouse, with continental glaciation of the southern pole. But did glaciation extend to uplands of equatorial latitudes? Our group has been testing this controversial hypothesis. Part of the evidence is a paleolandscape hypothesized to have been carved glacially. We have employed field- and lab analyses, geophysical and scientific drilling programs, and GIS analyses to assess this idea. If valid, what can this teach us about Earth’s climate? The late Paleozoic might seem remote in time, but it captures Earth’s most recent icehouse collapse on a fully vegetated planet.
Inferring climatic conditions from Earth’s “deep-time” (pre-Cenozoic) geologic record is challenging. We are examining how climate influences silicate weathering and thus derived sediments by sampling river sediment draining granitoid (i.e., granite and similar) rock types in hot-arid, hot-humid, cold-arid and cold-humid regions, including the desert southwest, Puerto Rico, Antarctica, Norway, and the glaciated part of equatorial Peru. Owing to the strong connection between rock weathering and atmospheric carbon, these results have implications for understanding how carbon cycles through the Earth system.