Professor of Practice
Ph.D., 1989, Florida State
Clay mineralogy, Diagenesis, Sedimentology, Marine geology, Stratigraphy
227 Bessey Hall
My research is on clay minerals as products of hydrothermal and pedogenic weathering, burial diagenesis, and as sedimentary particles bearing information on provenance and paleoclimates. Clays are best at paleoclimatic indicator when found in place, in paleosols, before being eroded and transported. Paleosols that are now in the deep sea, that were formed on subaerially erupted basalt flows prior to submersion, provide a near-ideal condition for interpreting paleoclimate and duration of landscape exposure prior to subsidence. Paleosols from three Ocean Drilling Program (ODP) legs: Leg 120 (southern Indian Ocean), Leg 144 (central Pacific Ocean), and Leg 152 (North Atlantic Ocean), now-submerged paleosols in varying states of development and preservation, proved fruitful for this type of study.
Clays might be used for paleoclimate studies, but in our lab we find that when they have been eroded and transported, they are better provenance indicators. Minor changes in clay content and composition helped us unravel what earthly sedimentologic process varied as Milankovich cycles drove variations in Paleocene sediment type on the Blake Nose, east coast of Florida (ODP Leg 171B). Provenenance signals from clay indicated the shift of sediment being shed from Iceland to sediment being shed from Greenland in the North Atlantic (ODP Leg 152).
Clays can reveal key details of weathering and diagenesis. My research on aged ocean basalt from ODP Leg 102 used clays to decipher the weathering of a mid-ocean ridge by seawater as it passed off-axis. Those weathering processes mimic those in a waterlogged soil. In a different vein, clay altered by high heat flow from the Ivory/Ghana coast of Africa (Leg 159) allowed dating of the opening of the South Atlantic Ocean along the Romanche Fracture Zone.
I serve on the Board for the Women's and Gender Studies Program at UNL and am currently doing research on the barriers to the advancement of geoscience women in academia. This interest grew out of my serving as President of the Association for Women Geoscientists in 2000-01.
I teach senior/graduate-level courses on Clay Mineralogy and on Sedimentary Core Description, and first-year courses on Physical Geology and Oceanography. We have an active outreach program, working with Girl Scouts and local schools to get girls into the field and hooked on geology.
Joint Oceanographic Institutes/U.S. Science Advisory Committee (JOI/USSAC) Distinguished Lecturer, 1995-96. Lecture Title: "Paleosols From the Deep Sea: ODP's Dirty Little Secret".
- Holmes, M.A., and O'Connell, S., 2008, Gender Parity in the Geosciences: data and geoscientists' perceptions, Nature Geoscience, 1(2), 79-82.
- Holmes, M.A., and O'Connell, S., 2007, Leaks in the Pipeline: Why do women remain curiously absent from the ranks of academia?, Nature, 446, 346.
- O'Connell, S., and M.A. Holmes, 2007, Retreating to advance women geoscience faculty, Eos Trans. American Geophysical Union, 88, 47.
- O'Connell, S. and Holmes, M.A., 2005, Women of the Academy and the Sea, Oceanography, 18(1), 12-24.
- Holmes, M.A., D.K. Watkins, and R.D. Norris, 2004, Paleocene cyclic sedimentation in the western North Atlantic, ODP Site 1051, Marine Geology, 209, 31-43.
- Holmes, M.A., O'Connell, S., Frey, C. and Ongley, L.K., 2003, Academic specialties shifting; hiring of women geoscientists stagnating, EOS, Transactions American Geophysical Union, 84(42), 457, 460-461.
- Holmes, M.A., O'Connell, S., Frey, C., and Ongley, L.K., 2001, The status of women in the geosciences, Geotimes, 48(9), 24-25.
- Holmes, M.A., 2000, Clay Mineral Composition of Glacial Erratics, McMurdo Sound, in Paleobiology and Paleoenvironments of Eocene Rocks, McMurdo Sound, East Antarctica (edited by Stilwell, J.D., and Feldmann, R. M. (eds.)), Amer. Geophys. Union, Washington, DC.
- Holmes, M.A., and O'Connell, S, Women Geoscientists' Writing Retreat, AWIS Magazine, 36(4), 22-23.
- Holmes, M.A., Physical Geology Laboratory Manual, v. 5, with Instructor's Manual, Houghton Mifflin Custom Publ., Boston, MA, 288 pp.