Subduction is among the most significant, yet enigmatic processes shaping our planet. Volcanism in oceanic and continental arcs is but one manifestation of major chemical exchange between the crust and mantle. Adding a precise temporal framework to this volcanic activity is a challenge rewarded by unique insights about the timing and rates of magmatic processes and the ways that volcanoes grow and erode. Moreover, these lava flows and tephras commonly contain valuable archives of global changes in the Earth's magnetic field and climate.

My research efforts are focused on the origin and evolution of arc magma, the timing and longevity of geomagnetic polarity reversals recorded by lava flows, and Quaternary paleoclimate in the southern hemisphere. Current projects involve geologic mapping and sample collection in the field, geochemical and isotopic characterization of volcanic rocks and their phenocrysts, paleomagnetic analysis, and dating using ⁴⁰Ar/³⁹Ar or cosmogenic surface exposure methods. Technological advances now poise the ⁴⁰Ar/³⁹Ar dating method to revolutionize the timescale for Pleistocene and even Holocene volcanism.

The Rare Gas Geochronology Laboratory under my direction houses equipment for both radioisotopic dating using ⁴⁰Ar/³⁹Ar methods and surface exposure dating using cosmogenic helium. The principal focus of research is on Quatenary volcanism. However, the versatility and precision of the ⁴⁰Ar/³⁹Ar geochronometer is being extended toward problems in structural geology, tectonics, sedimentary basin evolution, economic geology and petrology through collaboration with many Departmental and external faculty.

I am presently teaching:
Geology 610, Geochronology, Timescales, & Rates of Geological Processes
Geology 875, Graduate Research Seminar

During the past four years I have taught:
Geology 302, Physics and Chemistry of the Earth's Interior
Geology 203, Earth Materials
Geology 101, Elementary Geology
Geology 875, ⁴⁰Ar/³⁹Ar Geochronology
Graduate Seminars on magmatic processes
Graduate Field Seminar on Geology of Chile

Dept. Representative to Faculty Senate (2002-present)

Current Graduate Students:
John Hora
Sara Greene
Mike Smith (co-advisor w/Alan Carroll)
Bill Cassata (senior honors student)