Science

The present is a guide to the past, albeit an imperfect one, and the past is one of our best maps to the future: these two precepts guide much research in Earth history and Earth system processes, my own included. I am interested in questions like: How do records of biogeochemical processes get preserved in the rock record? What is the record of life from the early Precambrian to the Recent, and how does it reflect global biogeochemical conditions? What sorts of changes in global biogeochemical and climatic conditions have occurred in the past, and what lessons do these past changes hold for the future? The geological record is filled with evidence of alternate states of the Earth system: from the anoxic Earth of the Archean, to the Snowball Earths of the Paleoproterozoic and Neoproterozoic, to the Hothouse Earth of the Mesozoic and early Paleogene, to the Pleistocene Ice Age Earths. Understanding the nature of alternate Earths like these and the transitions between different states is the best way of testing models of Earth's future.

My current active research projects include:

• Pleistocene Sea Level and Future Ice Sheet Stability: How certain are we that sea level exceeded modern values during some previous interglacial periods? Where did the extra water come from, and how quickly?
• Early Eocene Paleoclimate on a Human Timescale: How did climate behave at sub-Milankovitch timescales during the early Eocene?
• A magnetofossil spike at the Paleocene-Eocene Thermal Maximum: What causes the magnetically anomalous properties previously observed in the Paleocene-Eocene boundary clay of New Jersey? How wide-spread are such properties, spatially and temporally?

Past projects include:

• Preservation of magnetization in carbonate sediments: In carbonate platform sediments, what are the sources of magnetization and what controls their preservation?
• The Paleoproterozoic Snowball Earth and the Rise of Oxygen: What was the nature of the transition from an anoxic to an oxygenated Earth?
• Ferromagnetic resonance and rock magnetic identification of magnetotactic bacteria: How can we identify fossil magnetotactic bacteria?