Members of the Geophysics Group at UWM use techniques like gravity, magnetism, and seismology to study Earth’s deep structure; to interpret tectonic and volcanic processes; and to understand how Earth’s magnetic field changes in time and space. Geophysical techniques provide a window into the Earth, allowing us to examine everything from Earth’s innermost core to natural resources in the shallowest crust.

Julie BowlesJulie Bowles

Dr. Julie Bowles, Assistant Professor

Specializes in Geophysics, Paleomagnatism

Research: Most of my research centers around the field of paleomagnetism—the study of Earth’s magnetic field as recorded in rocks and sediments. My work can be subdivide into three main areas: 1) understanding how Earth’s magnetic field has changed over time; 2) using these “rock records” of changing magnetic fields and magnetic properties to interpret volcanic processes; and 3) understanding how and how well magnetic minerals record the field.

    1. Earth’s magnetic field varies in both space and time. Characterizing and understanding those variations can help us to understand the processes in Earth’s core that generate the magnetic field. They can also help to provide constraints on planetary differentiation, inner core nucleation, and atmospheric evolution. Current work in this area involves using volcanic glass from the Juan de Fuca Ridge to better constrain field variations over the past few tens of thousands of years, and evaluating ignimbrites and other pyroclastic flows as potential field recorders over longer timescales.
    2. By comparing records of the Earth’s field recorded in igneous rocks with known variations in in the field, we can place some age constraints on lava flows or estimate whether or not two flows were likely erupted at the same time. Additionally, by studying the orientation of magnetic minerals in some igneous rocks like ignimbrites, we can learn something about flow direction and source location. Ongoing work in this area includes examining eruption timing and recurrence intervals on the Juan de Fuca Ridge and the Galapagos Spreading Center; and examining flow direction and post-emplacement rotations in pyroclastic flows.
    3. We use paleomagnetic data to provide constraints on tectonic reconstructions, geodynamo formation and behavior, planetary evolution, magmatic flow, and sub-solidus deformation. To reliably draw these kinds of conclusions, it is necessary to fully understand the mechanisms by which magnetic minerals form and acquire magnetization and the temperature at which this happens. How reliable are our paleomagnetic recorders? Recent work in this area has involved creating synthetic Mars rocks to better understand the strong magnetic anomalies on Mars; and creating synthetic basaltic glass to understand the timing of magnetite formation in submarine eruptions and its implications for the type of magnetization they acquire.

Any interested MS or PhD students should feel free to contact the faculty member above.