My research focuses on landscape evolution and response to changing climate since the last glaciation. This focus has expressed itself on a number of topics over the past decade...
Alpine Landscape Evolution
My Ph.D. dissertation with Missy Eppes and John Diemer at UNC Charlotte focused on alpine and sub-alpine landscape response to millenial scale climate change in the San Juan Mountains. Using mapping and soil descriptions, we found that landscapes in the area tend to be reactive to rapid changes in climate more than either periods of warm climate or periods of relatively cold climate. As part of the study we developed a new paleoclimate record from Cumbres Bog using palynology (Gonzalo Jimenez-Moreno) and diatoms (Jeffery Stone).
I continue to work in the area with a new colleague (Jacquie Smith at the College of St. Rose) on the timing of large landslides in the area. We are currently attempting to date the timing of landslides via 3 different methods: comosgenic dating, radiocarbon dating of basal bog sediments, and relatively soil development. As of the field season 2012, we have examined and sampled from 5 different landslides in the region. GSA 2012 Poster (Large) by student authors Kelsey Krueger and Catherine Schmidt who worked on cores and soils both in the field and in the lab.
While at Idaho State University, I worked with Glenn Thackray on the distribution and rock glaciers in the Lemhi Range of central Idaho. We mapped more than 40 rock glaciers which had not previously been identified and tied their distribution to predictable factors (topographic shading) and also to less predictable factors (lithology).
The distribution and formation of rock glaciers continues to be an interest of mine, specifically in the San Juan Mountains where they have been widely reported.
Streams accross the pidemont of North Carolina are consistently incised 1-3 meters. While it is logical to assume that the incision is due to the legacy sediments previously impounded behind mill dams, preliminary field work has shown that piedmont streams are commonly incised into saprolite and not into laminated sediments. I have begun a more thorough investigation of streams in the Davidson area with Davidson students.
My Hope College research project with Ed Hansen focused on the migration and internal structure of dunes along the lake shore of Lake Michigan. I am currently pursuing funding to return to studying dunes along the Great Lakes.
Johnson, B.G., Moreno, G.J., Eppes, M.C., Diemer, J.A., Paleoclimate implications from a 12 meter bog core in the southern San Juan Mountains, Colorado, in review, The Holocene, submitted 8/12.
Layzell, A.L., Eppes, M.C., Johnson, B.G., Post-glacial range of variability in the Conejos River Valley, southern Coorado, USA: fluvial response to climate change and sediment supply, Earth Surface Processes and Landforms, 37, 1189-1202, 2012.
Johnson, B.G., Layzell, T., Eppes, M.C., A soil chronosequence from the Upper Conejos Valley, Colorado, in prep for submission to Catena, est. submittal date 4/13.
Johnson, B.G., Eppes, M.C., Diemer, J.A., Landscape response to millennial scale climate change after the Last Glacial Maximum, San Juan Mountains, Colorado, Quaternary Research, 76, 352-62, 2011.
Hansen, E.C., Bodenbender, B.E., Johnson, B.G., Kito, K., Davis, A.K., Havholm, K.G., and Peaslee, G.F., The Origin of Dark Sand in Eolian Deposits along the Southeastern Coast of Lake Michigan, Journal of Geology, 119, 487-503, 2011.
Johnson, B. G., Eppes, M.C., Diemer, J.A., Surficial geologic map of the Upper Conejos River drainage, southeastern San Juan Mountains, southern Colorado, Journal of Maps, v2010, 30-39, 2010.
Johnson, Bradley G., Alpine and subalpine landscape response to post-glacial climate change in the San Juan Mountains: a comparison of new landscape and climate records, Ph.D. Dissertation, 2010.
Johnson, Bradley G., Thackray, Glenn D., VanKirk, Rob, The Effect of Topography, Latitude, and Lithology on the Distribution of Rock Glaciers in the Lemhi Range, central Idaho, Geomorphology, 91, 38-50, 2007.
Johnson, Bradley G., The Effect of Topography, Latitude, and Lithology on the Distribution of Rock Glaciers in the Lemhi Range, central Idaho, M.S. Thesis, 2006.
Brad Johnson - Davidson College - Enivronmental Studies Program
Office: Watson 283 - Research Lab: Watson 260 - Phone: 704-894-2096 - Cell: 704-840-4087