The University of Iowa

Bradley Cramer

Bradley Cramer
Assistant Professor
(319) 335-0704
35B TH
Research Interests: 
Bio-Chemostratigraphy and Earth History Research

Earth System Science, deep-time Earth history, stable and radiogenic isotope geochemistry, chemostratigraphy, biostratigraphy, stratigraphic nomenclature, history of geology, geochronology, and the Geologic Time Scale. Effectively, I try to understand the major biotic, chemical, and physical events that punctuate the history of our planet by throwing every tool and proxy at the problem as is possible. Currently, I am the project leader for the International Geoscience Programme (IGCP) Project 591 – The Early to Middle Paleozoic Revolution. You can visit our website and join the project at

Cramer, B.D., Condon, D.J., Söderlund, U., Marshall, C., Worton, G.J., Thomas, A.T., Calner, M., Ray, D.C., Perrier, V., Boomer, I., Patchett, P.J., & Jeppsson, L. U-Pb (zircon) age constraints on the timing and duration of Wenlock (Silurian) paleocommunity collapse and recovery during the ‘Big Crisis’. (in press with GSA Bulletin).

Melchin, M.J., Sadler, P.M., & Cramer, B.D., 2012 Chapter 21: The Silurian Period, in Gradstein, F.M., Ogg, J.G., Schmitz, M. & Ogg, G., (eds.), The Geologic Time Scale 2012, Elsevier, New York, p. 525-558.

Cramer, B.D., Munnecke, A., Schofield, D.I., Hasse, K.M., & Haase-Schramm, A., 2011.  A revised 87Sr/86Sr curve for the Silurian: Implications for global ocean chemistry and the Silurian timescale. Journal of Geology, v. 119, p. 335-349.  doi: 10.1086/660117.

Cramer, B.D., Loydell, D.K., Samtleben, C., Munnecke, A., Kaljo, D., Männik, P., Martma, T., Jeppsson, L., Kleffner, M.A., Barrick, J.E., Johnson, C.A., Emsbo, P., Joachimski, M.M., Bickert, T., & Saltzman, M.R., 2010. Testing the limits of Paleozoic chronostratigraphic correlation via high-resolution (<500,000yrs) integrated conodont, graptolite, and carbon isotope (δ13Ccarb) biochemostratigraphy across the Llandovery-Wenlock (Silurian) boundary: Is a unified Phanerozoic timescale achievable?. Geological Society of America Bulletin, v. 122, p. 1700-1716, doi: 10.1130/B26602.1.