Dawn Sumner's Group

Geology Department
University of California, Davis


Current Post Doc:

Bekah Shepard is continuing her work on understanding mat morphology and how motility influences it.

Current Graduate Students:

Cara Harwood is a Ph.D. student working on the origins of thrombolites.
Tyler Mackey is a M.S. student working on microbial mats in Antarctica.
Amy Williams is a Ph.D. student working on microbial signatures in rocks relevant to those found on Mars.

Current Undergraduate Students in the Group:

More coming soon... probably Alexandria Hernandez...


Graduate students who completed graduate degrees with me:

Cara Harwood finished her M.S. thesis in spring 2009 on the origins of thrombolites in the Beck Spring Formation, eastern CA. She is now doing a Ph.D. with me working on the origins of thrombolites.

Thesis Title: Multiple Origins of Diverse Microbial Fabrics in Co-occurring Thrombolitic and Stromatolitic Structures from the Neoproterozoic Beck Spring Dolomite

Bekah Shepard completed her Ph.D. in spring 2009. She worked on the morphology of microbial communities and cyanobacterial motility influences morphology for her Ph.D. thesis. She also characterized microbial communities in Lake Pavillion, B.C. She is currently a post doc with me.

Thesis Title: The Significance of Cell Motility to Microbial Community Morphogenesis

James Bishop (M.S. 2004) completed his Ph.D. in Winter 2008 with Isabel Montanez, Dave Osleger and me. He is currently working as a geologist at Chevron, San Ramon, CA.

Thesis Title: Sedimentation and Diagenesis During the Late Paleozoic Ice Age: Arrow Canyon, Nevada, and the Capitan Backreef, Slaughter Canyon, New Mexico.

Greg Chavdarian completed his M.S. degree in Spring 2008. He characterized cracking mechanisms in sand at White Sands National Monument and studied the enchange of water vapor between the sand and the atmosphere. He is currently working as a geologist in the petroleum industry.

Thesis Title: Polygonal Cracks and Mineral-Atmospheric Water Cycling in Hydrous Sulfate Sands:  An Analog to Martian Outcrops.

Nik Huerta finished his M.S. thesis in Winter 2007 on neutron CT imaging techniques at McClellan Nuclear Radiation Center after completing his senior thesis in December 2003. His focused on developing methods for evaluating porosity in sandstones, including using computational and mathematical approaches to evaluating images. Nik is pursuing a masters in petroleum engineering at UT Austin.

Thesis Title: Neutron Computed Tomography and Porosity in Geologically Relevant Samples.

Megan Murphy completed her Ph.D. in Fall 2006 on microbial tube structures, fenestrate microbialites and facies in the Neoarchean Carawine Formation, Western Australia. Megan will start an internship at Chevron in the San Ramon Carbonate Research Group in February 2007.

Thesis Title: Variations in Microbialite Morphology with Depositional Environment in a Precambrian Ramp Deposit, Hamersley Group, Western Australia.

Maris Tabor completed her M.S. thesis in 2004 on neutron CT imaging techniques at McClellan Nuclear Radiation Center. Her focus was on calibrating the attenuation characteristics of carbonates and organics to image ancient microbial structures.

Thesis Title: Applications of Neutron Computed Tomography for 3-D Imaging of Microbial Structures in Archean Carbonates.

  • James Bishop finished his M.S. thesis in Winter 2004. He continued his research as a Ph.D. student at UCD and now works for Chevron. See his papers on the origin of molar-tooth structures
    Thesis Title: A New Model for Molar Tooth Structure, Facies, and Stratigraphy of the Neoarchean Monteville Formation, Transvaal Supergroup, South Africa
  • Kat "Phoenix" Perkins (once Bergk) finished her M.S. thesis in Spring 2003. May Kat's new feathers remain strong and beautiful for years to come!
    Thesis Title: Sequence Stratigraphy of a Portion of the Lower Cambrian Grand Cycle C, Southwestern Nevada and Southeastern California.
  • Nat Stephens finished his Ph.D. thesis in Spring 2002 on Late Devonian microbial reefs and carbon isotopes of the Canning Basin, Australia. Nat is currently working as a geologist for ExxonMobil.
    Thesis Title: Late Devonian Stratigraphy, Stable Isotopic Analyses, and Paleoecology in the Napier, Oscar, and Emanuel Ranges, Canning Basin, Western Australia.
  • Sarah Tourre finished her M.S. thesis in Fall 2000 on Eocene herringbone calcite. Last I heard, Sarah is working as a Staff Geologist in the environmental consulting industry.
    Thesis Title: Cave-Filling Herringbone Calcite: Morphology and Geochemistry of an Unusual Carbonate Cement from Egypt.

Dawn Sumner and Nat Stephens on graduation day.

Undergraduate students who completed Senior Theses (or other work) with me:

Post Docs Who've Worked With Me:



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Dawn Y. Sumner
Department of Geology
University of California
Davis, CA 95616
dysumner@ucdavis.edu