Faculty and Staff Directory

Introduction

As a geophysicist who studies the magnetic properties of earth materials, my scholarship and teaching are at the boundary between geophysics and mineralogy. Magnetic particles are nearly ubiquitous in geological and environmental materials; by understanding the properties of magnetic materials, we can distinguish sediment sources, identify environmental conditions and trace depositional processes. Rock magnetism allows the analysis of mineralogy, chemistry and grain size of magnetic particles, even at the 1 micrometer to 1 nanometer sizes and parts-per-billion concentrations characteristic of soils, sediments and airborne dust. The focus of my work is on examining the processes that form magnetic particles, and the significance of these particles in both sediments and igneous rocks, especially as regards orientation distributions of minerals in rocks and sediments.

Current Research

Students and I use the tools of rock magnetism and standard mineralogical techniques to identify contaminant sources, investigate past climate change, trace magmatic processes and explore the fundamental magnetic properties of minerals. Specific research projects include:

• Identifying the causes and significance of magnetic anisotropy: Most rocks and sediments become magnetized more easily in some directions than others a property called magnetic anisotropy. This is usually due to the orientation or distribution of magnetic particles in those rocks. Detailed rock magnetic studies that allow us to understand what minerals are responsible for magnetic anisotropy can help geologists interpret all sorts of geological processes from magma chamber dynamics to the flow of glacial outwash streams. Current and future opportunities for student research in this area include examining interglacial streamflow directions in the Puget Trough, windblown sediment in the Palouse and pluton emplacement in the Cascades, and improving the sensitivity of analytical techniques.
   
• Developing magnetic proxies for paleoclimate and pollution based on the weathering and formation of iron minerals in loess and soil: Iron minerals are sensitive to moisture, and previous work has indicated that iron minerals in soils do indeed track variations in rainfall. However, questions remain about the exact relationship between iron minerals with their distinctive magnetic properties and paleoclimate, particularly in areas of low rainfall such as the Palouse in Eastern Washington. Understanding the formation and weathering of iron minerals in soils can give us a natural background against which to evaluate magnetic properties related to soil contamination. Future opportunities for student research in this area include magnetic characterization of soils and windblown silt deposits (loess) from the Palouse and from Argentina, and soil from the South Puget Sound.

Teaching

Research on learning indicates that students understand scientific concepts more deeply and retain those concepts longer when they engage with the material interactively. To this end, I incorporate a modeling-based approach in the introductory physics sequence that gets students to construct conceptual and mathematical models to explain physical concepts. In geoscience courses, I use data-rich, hands-on activities and Google Earth to probe students' conceptions of how the Earth works. Courses I teach include:

• TESC 117: Physical Geology
• TESC 121/122/123: Calculus-Based Introductory Physics Sequence (mainly TESC 122, Electromagnetism and Oscillatory Motion)
• TESC 227: Earth History
• TESC 243: Geography of the Physical Environment
• TESC 347: Environmental Earth Materials
• TESC 417: Field Geology

I am also developing materials for the InTeGrate Project, which is administered by Carleton Colleges Science Education Resource Center (http://serc.carleton.edu/integrate). The goal of InTeGrate is to merge the teaching of geoscience and sustainability in an active learning framework.

Affiliations

• American Geophysical Union
• Geological Society of America
• Mineralogical Society of America
• National Association of Geoscience Teachers
• American Association of Physics Teachers
• InTeGrate Program, Carleton College Science Education Resource Center
• UW Tacoma Quantitative Fellows

Academic Service

• Reviewer, National Science Foundation (geophysics and education directorates); Geochemistry, Geophysics, Geosystems; Earth Planets Space; Earth and Planetary Science Letters; Geophysical Journal International; On the Cutting Edge: Professional Development for Geoscience Faculty
• Presenter: National Association of Geoscience Teachers Short Course, "Teaching with Google Earth," 2011 Geological Society of America Meeting
• Resource Faculty, Curriculum for the Bioregion 2010 Geoscience Faculty Learning Community

Honors and Awards

• 2010 Visiting Fellow, Institute for Rock Magnetism