Brad Johnson - Elk Preserve





























































































 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 





 

Research


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...

Sub-alpine Landscape EvolutionStream in 2nd Elk Meadows - San Juan Mountains

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 recently finished a project in the area (with Jacquie Smith at Union College and John Diemer at UNCC) on the timing of large landslides in the area. The project aimed to date the timing of landslides via 3 different methods: comosgenic dating, radiocarbon dating of basal bog sediments, and relatively soil development. The results are in Earth Surface Processes and Landforms: http://onlinelibrary.wiley.com/doi/10.1002/esp.4168/full

A student, Kelsey Krueger, and I, also published a paper looking at the prevalence of beaver dams on landslides. Those results are in Physical Geography:  http://www.tandfonline.com/doi/abs/10.1080/02723646.2016.1218723

I have now begun looking at the extensive terrace sequence near South Fork Colorado along the Rio Grande with Jacquie Smith and Jared Beeton (Adams State). We have dug a number of soil pits and sampled for OSL. Results in the near future.

 

Catherine and Kelsey

 

Dunes

My Hope College research project with Ed Hansen focused on the migration and internal structure of dunes along the lake shore of Lake Michigan. My student, Emma Fulop, has mapped the stratigraphy of the Green Point Dune Complex in northern Michigan and wil continue to work on the timing as a continuation of her senior capstone. We are currently waiting on OSL results.

Stream Discharge in Davidson

Carolyn Macek and I (along with John Mazurek at the USGS) installed stream gauges along streams on campus in the fall of 2013. That project continued with Abby Preston and eventually we applied for a Duke Water Resources Grant to expand the project. With the support of the fund, we have installed 18 stream gauges in the Davidson area on small headwater streams. We continue to collect depth (converted to discharge), temperature, and conductivity in all of those streams. We also have rain gauges throughout the area. Catie Morris and Caitlin Reilly worked on the project through the spring of 2017 while Peter Whitehouse and Heather Mase have worked on it starting in summer 2017. We have collected hundreds of thousands of data points and potential collaborators are encouraged to contact me. Publications are forthcoming but there are an unlimited number of questions that could be asked of the dataset. Very few studies have looked at headwater streams in this way.

Piedmont Landscapes

My more recent research with students has tended to focus on the local Piedmont. Specifically, my students and I have been looking at stream incision in the Piedmont and the timing of gully erosion. I expect these manuscripts to be submitted in 2018.

Soil and Landscape Response to Wildfires

After the wildfires that occurred in the fall of 2016 throughout the Blue Ridge, we began looking at soil and landscape response to fires in the area. In South Mountain State Park, we've looked at soil profiles from different landscape positions in the burned area and also outside the burned area. We are in the process of sorting out differences in soil properties. We've also been looking at hydrophobicity and related runoff. Our preliminary results suggest that hillslopes are shedding signifficantly more water in burned areas than in unburned areas.

Selected Publications

Johnson, B.G., Smith, J., Diemer, J.A., A chronology of post-glacial landslides suggests that slight increases in precipitation could trigger a disproportionate geomorphic response. Earth Surface Processes and Landforms, (online first), 2017, DOI: 10.1002/esp.4168.

Johnson, B.G., Rock Glaciers in the San Juan Mountains, New Mexico Geological Society Guidebook 68, Geology of the Ouray-Silverton Area, 199-202, 2017.

Johnson, B.G., Gillam, M., Beeton, J., Glaciations of the San Juan Mountains: A review of work since Atwood and Mather, New Mexico Geological Society Guidebook 68, Geology of the Ouray-Silverton Area, 173-182, 2017.

Beeton, Jared, Johnson, Bradley, Rivers, Glaciers, and Mammoths, Geomorphic Research in the San Luis Valley, invited chapter in edited volume on the human and natural history of the San Luis Valley, volume accepted for publication by University of Colorado Press, in press.

Krueger, Kelsey*, Johnson, B.G., The effect of sub-alpine landslides on headwater stream gradient and possible sites for beaver inhabitation, Physical Geography, 37, 344-360, 2016.

Johnson, B.G., Layzell, T.L., Eppes, M.C., Assessing the impact of parent material and landscape position on a soil chronosequence in sub-alpine, post-glacial deposits in the southeastern San Juan Mountains of Colorado, Catena, 127, 222-39, 2015.

Johnson, B.G., Recommendations for a system to photograph core segments and create stitched images of complete cores, Journal of Paleolimnology, 53, 437-44, 2015.

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., 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: Wall 272 - Research Lab: Wall 125 - Phone: 704-894-2096 - Cell: 704-840-4087
E-mail: brjohnson:AT:davidson:DOT:edu