Dr. Phil Armstrong

Contact Information




Phil Armstrong



Ph.D. Geophysics, University of Utah

Research Areas

Colleagues often ask me what kind of geologist I am. Guess you’d have to say I’m a structural geologist that focuses on the processes and products of the vertical motion of crustal rocks and Earth’s surface at time scales of thousands to millions of years. This research involves both the uplift of rocks, the exhumation of once deeply buried rocks, and basin development. These rocks are generally, but not always, in mountain belt settings such as the Wasatch Mountains in Utah, the mountains of southern California, or the huge mountains of Alaska. My students and I use basic field methods, low-temperature thermochronometry, landform analysis, and geophysics to evaluate uplift and/or exhumation events.

As with my research, my teaching seems to be very diverse. I teach several courses including Geologic Field Techniques, Introduction to Geophysics, Structural Geology, Summer Field Geology, Geology of National Parks (a General Education course), Quaternary Tectonics, and various other graduate-level courses and special topics. All of these courses, with the exception of the National Parks course, have numerous field trips and extensive field and related lab projects. We’re lucky here in southern California because we have what I like to call “Geologic Disneyland” in our backyard – the opportunities for field work in our courses are incredible. My co-workers and I seem bent on wearing out our field vehicles getting to field sites.


Ferguson, K.M, Armstrong, P.A., Arkle, J.C., and Haeussler, P.J., 2015,
Focused rock uplift above the subduction décollement at Montague and Hinchinbrook Islands, Prince William Sound, Alaska: Geosphere, v. 11, 144-149doi:10.1130/GES01036.1.

Haeussler, P.J., Armstrong, P.A., Liberty, L.M., Ferguson, K.M., Finn, S.P., Arkle, J.C., and Pratt, T.L., 2014, Focused exhumation along megathrust splay faults in Prince William Sound, Alaska, Quaternary Science Reviews, http://dx.doi.org/10.1016/j.quascirev.2014.10.013.

Fitzgerald, P.G. Roeske, S.M., Benowitz, J.A., Riccio, S.J., Perry, S.E., Armstrong, P.A., 2014, Alternating asymmetric topography of the Alaska Range along the strike-slip Denali Fault: Strain partitioning and rheologic control across a terrane megasuture,Tectonics, DOI: 10.1002/2013TC003432.

Arkle, J.C., Armstrong, P.A., Haeussler, P.J., Prior, M.G., Hartman, S., Sendziak, K.L., Brush, J.A., 2013, Focused exhumation in the syntaxis of the Chugach Mountains and Prince William Sound, Alaska, Geological Society of America Bulletin, May 2013, v. 125, no. 5-6, p. 776-793, doi:10.1130/B30738.1.

Langenheim, V., Surko, T.L., Armstrong, P.A., and Matti, J.C., 2012, Basin thickness variations at the junction of the Eastern California Shear Zone and the San Bernardino Mountains, California: how thick could the Pliocene section be? Reynolds, R.E. (editor), Searching for the Pliocene: Southern Exposures, The 2012 Desert Research Symposium, California State University Desert Studies Center, 31-37.

Benowitz, J.A., Layer, P.W., Armstrong, P.A., Perry, S.E., Haeussler, P.J., Fitzgerald, P.G., Vanlangenham, S., 2011, Spatial Variations in Focused Exhumation Along a Continental-Scale Strike-Slip Fault: the Denali Fault of the Eastern Alaska Range, Geosphere. 7, 455-467, doi: 10.1130/GES00589.1

Armstrong, P.A., Owen, L., A., Perez, R.A., and Finkel, R.C, 2010, Timing and controls on late Quaternary landscape development along the eastern Sierra El Mayor range front in northern Baja, California, Mexico, Geomorphology, doi: 10.1016/j.geomorph.2009.08.005

Armstrong, P.A., Haeussler, P., and Garver, J., 2008, Field excursion from Anchorage to Seward, Alaska, FT2008 – 11th International Conference on Thermochronology, Anchorage, AK, 16 pp.

Davis, M. G., D. S. Chapman, T. M. Van Wagoner, and P. A. Armstrong, 2007, Thermal conductivity anisotropy of metasedimentary and igneous rocks, J. Geophys. Res., 112, B05216, doi:10.1029/2006JB004755.

Taylor, A., Armstrong, P.A., and Knott, J.R., 2006, Geomorphology And Geochronology Of The San Juan Creek Terraces: Implications For Quaternary Uplift Of The Santa Ana Mountain Foothills, Orange County, California; South Coast Geological Society 2006 Field Trip Guidebook, p. 135-156.

Armstrong, P.A., 2005, Thermochronometers in Sedimentary Basins (INVITED), in Thermochronology: Techniques, Interpretations, and Applications. P.W.Reiners, T.A.Ehlers (eds.). Reviews in Mineralogy and Geochemistry, 58, 499-525.

Armstrong, P.A., Taylor, A.R. and Ehlers, T.A., 2004, Is the Wasatch fault footwall (Utah, USA) segmented over million year time scales? Geology, 32, p. 385-388.

Armstrong, P.A., Ehlers, T.A., Chapman, D.S., Farley, K.A., and Kamp, P.J.J., 2003, Exhumation of the Central Wasatch Mountains, 1: Patterns and timing deduced from Low-temperature Thermochronometry data, Journal of Geophysical Research, V. 108, 2172, doi:10.1029/2001JB001708.

Ehlers, T.A., Willett, S.D., Armstrong, P.A., and Chapman, D.S., 2003, Exhumation of the Central Wasatch Mountains, 2: Thermo-kinematics of exhumation, erosion, and thermochronometer interpretation, Journal of Geophysical Research, V. 108, 2173, doi:10.1029/2001JB001723