Kellie Wall, Ph.D.

My research combines field surveying and mapping, geochronology techniques, and petrologic and geochemical study of volcanic rocks. In the field, I use stratigraphic relationships and physical characteristics of volcanic products to interpret relative timing of past eruptions and what those eruptions were like. Rock samples from different volcanic units are then taken back to the lab for various types of analyses. To determine ages of eruptions, I use a variety of tools such as 40Ar/39Ar dating, zircon U-Pb dating, cosmogenic nuclide surface-exposure dating, and paleomagnetic analysis. I observe textures and mineral contents of volcanic samples under microscope to gain clues about how magmas were formed, stored, and transported through the crust. Chemical compositions of the rocks and their minerals, determined by techniques such as X-ray fluorescence or electron microprobe analysis, allow me to further investigate magma conditions and processes, and whether these were the same or different prior to distinct eruptive episodes. Ultimately, with this work I aim to unveil any patterns in the locations or styles of past eruptions, and the types of magmatic processes that precede eruptions, in order to better understand potential hazards in similar volcanic areas.

Currently, I am investigating the “recent” (past tens to hundreds of thousands of years) eruptive history of the San Francisco Volcanic Field, a distributed volcanic field near Flagstaff, Arizona that has been periodically active since about six million years ago. I have also worked on reconstructing the volcanic history of the Goat Rocks Wilderness area in the Cascade Mountains of Washington State, where several composite volcanoes (similar to Mount Hood) were constructed over a period of about three million years and are now extinct.