Dawn Sumner's Group Geology Department University of California, Davis

Current Graduate Students:

James Bishop (M.S. 2004) recently published 2 papers the origin of molar-tooth structures based on his M.S. thesis research. James did a Senior Thesis on bioherms in slope sediments of the Late Devonian Canning Basin, Australia with Nat, me, and Clint Cowan (his main advisor, at Carlton College). He is continuing his graduate research on Permian carbonates working with Isabel Montanez, Dave Osleger and me.

Bekah Shepard is working on the morphology of microbial communities and cyanobacterial motility influences morphology for her Ph.D. thesis.

Greg Chavdarian is comparing structures at White Sands National Monument with those on Meridiani Planum, Mars, as observed by the rover Opportunity. He is performing field monitoring and experimentally producing cracks in sand. Here are links to his senior thesis (220 KB pdf) and figures (14 MB pdf) on White Sands and Meridiani Planum. Results were also published in Geology in 2006.

Current Undergraduate Students in the Group:

Amy and Dana are also starting to work with Bekah. Their first focus is on time lapse imaging of cyanobacterial motility.

Nicole Thompson is studying carbonate chemistry in water and media with the hopes of understanding CO2 limitation in cyanobacterial cultures.

Dominique Waters is researching the water quality of the Arboretum Waterway in collaboration with the course Geology of Campus Waterways. She is particularly interested in water density and stratification.

Photos of my field assistant. He says "woof", which means he prefers to study squirrels over rocks.

Graduate students who completed graduate degrees with me:

Nik Huerta (2007) is almost finished with his masters 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:

Megan Murphy completed her Ph.D. in 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 is continuing his research as a Ph.D. student at UCD. 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:

• Patrick Senge (2006) worked with Megan Murphy on reconstructing the 3-D geometry of tube structures from Neoarchean carbonates using serial sectioning. Patrick is now a mine geologist working in Nevada.
  Thesis Title: Development of the Late Archean Microbialite Support and Drape Structures of the Gamohaan Formation, Transvaal Supergroup, South Africa
• Greg Chavdarian (2005) worked and is working on understanding how cracks and fins in sulfate sands form on earth and on mars. Here are links to his thesis (220 KB pdf) and figures (14 MB pdf).
  Thesis Title: Cracks and Razorbacks: Pieces of Mars at White Sands National Monument, New Mexico.
• Katie Alexander (2005) wrote a Senior Thesis investigating how cyanobacterial mats respond to water flow and how they bind sand-sized sediment. She created "Microbially Induced Sedminary Structures" in the lab. She worked closely with Bekah and is now in graduate school at ASU.
  Thesis Title: "MISS" in a Laboratory Setting: Observations and Mechanisms of Formation.
• Gina Lee (2004) worked on characterizing erosion of Cache Creek near Guinda, CA for her thesis. She is now working in environmental consulting in southern California.
  Thesis Title: Thirty-nine Years of Cache Creek Migration and Embankment Erosion
• Nik Huerta (2003) worked on developing neutron imaging techniques at McClellan Nuclear Radiation Center and applied them to studies of porosity and organic compounds in rocks (Abstract of his AAPG poster presentation). He continued this research as a masters student at UCD and is now in a petroleum engineering masters program at UT Austin.
  Thesis Title: Neutron Computed Tomography: A Characterization of the System at McClellan Nuclear Radiation Center and Presentation of Groundwork Research for Use in Sedimentary Geology.
• Jason Snyder (2002) graduated spring 2002 after working on the stable isotopic geochemistry of Egyptian herringbone calcite. Jason just finished a M.S. in atmospheric sciences at UCDavis.
  Thesis Title: Determination of Calcite Age through Paleoclimatology.
• Marie Reil graduated fall 2001. She worked on compiling the geology of Shell Ridge in Walnut Creek, CA. She is working in water quality these days.
• Tracy Fenger (2000) wrote a thesis on the Neoproterozoic Rainstorm Member of the Johnnie Formation (Abstract of her GSA poster presentation). Tracy also helped with my calcite precipitation experiments. After working for an environmental consulting firm for several years, she is now a graduate student studying paleoclimatology at UNC Department of Geological Sciences.
  Thesis Title: A Glacial Interpretation of the Rainstorm Member of the Johnnie Formation, Eastern California

Post Docs Who've Worked With Me:

• Ryioji Shiraki worked part time on calcite precipitation experiments and helped with elemental analyses of carbonates.

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