Dennis J. Geist
Dennis J. Geist
- Ph.D., Geology, 1985—University of Oregon, Eugene
- B.A., Earth Sciences, 1980—Dartmouth College, Hanover, New Hampshire
- Igneous petrology
- Geology and island biodiversity
- The Galapagos, Northern Andes, Snake River Plain, Iceland, Antarctica
- Chadwick, W.W., Jónsson, S., Geist, D.J., Poland, M., Johnson, D.J., Batt, S., Harpp, K.S., and Ruiz, A. 2011. The May 2005 eruption of Fernandina volcano, Galápagos: The first circumferential dike intrusion observed by GPS and InSAR, Bulletin of Volcanology 73, 679-697.
- Geist, D., Hamman, O., Snell, H. and Whelan, P. 2011. Galapagos Goal: Eradication of Invasive Plants, Science, ISSN 1095-9203.
- Poulakakis, N., Russello, M., Geist, D., and Caccone, A. 2011. Unraveling the Peculiarities of Island Life: Vicariance, Dispersal and the Diversification of the Extinct and Extant Giant Galápagos Tortoises, Molecular Ecology, doi: 10.1111/j.1365-294X.2011.05370.x
- Geist, D. 2009. Islands on the Move: Significance of Hotspot Volcanoes, in Du Roy, T, ed. Galapagos: Preserving Darwin's Legacy, Firefly Books, Ontario, Canada.
- Geist, D. and Harpp, K. 2009. Galapagos Islands, Geology, Encyclopedia of Islands, Gillespie and Clague, eds. University of California Press, 367-372.
- Geist, D., Dieffenbach, B., Fornari, D., Kurz, M., Harpp, K., and Blusztajn, J. 2008. Construction of the Galapagos platform by large submarine volcanic terraces, Geochemistry Geophysics Geosystems, 9, doi:10.1029/2007GC001795, 2008.
- Geist, D., Harpp, K., Naumann, T., Poland, M., Chadwick, W., Hall, M., and Rader, E. 2008. The 2005 eruption of Sierra Negra volcano, Galápagos, Bulletin of Volcanology, 70, 655-673.
- Mayhew, L., Geist, D., Childers, S., and Pierson, J. 2007. Microbial community comparisons as a function of the physical and geochemical conditions of the Galapagos Island fumaroles, Geomicrobiology Journal, 24, 615-625.
- Beheregaray, L.B., Ciofi, C., Geist, D., Gibbs, J.P., Caccone, A., and Powell, J.R. 2003. Genes record a prehistoric volcano eruption in the Galápagos, Science 302, 75.
- Geist, D., Teasdale, R., Sims, E., and Hughes, S. 2002. Subsurface volcanology at TAN and controls on groundwater flow, GSA Special Paper 353, 45-59.
- Geist, D. and Garcia, M.O. 2000. The role of science and independent research during volcanic eruptions, Bulletin of Volcanology 62, 59-61.
- Darwin Bicentennial
2009 celebrates the 200th birthday of Charles Darwin and the 150th anniversary of Origin of Species. Major events are being planned by the Darwin Foundation, University of Cambridge, and AAAS. We are participating in these, focusing on the impact of Galapagos on Darwin's ideas and his contributions to geology.
- Petrologic controls on volcanic eruptions
Hekla volcano in Iceland has a remarkable behavior, where the explosivity of the eruptions correlates to the repose interval and the extent of differentiation. We are testing the hypothesis that crystallization is not an important factor in the evolution of the magma chamber, but instead happens in an open conduit, which links the deep chamber to the surface. The work involves detailed textural and geochemical studies of the phenocrysts in all of the tephras and lavas that have erupted since 1104 AD.
- Galapagos magma chambers
Through accurate GPS measurements and ongoing studies of the eruptive rocks, we are delineating the geometries and thermal histories of the subcaldera magma bodies in the western Galapagos.