Geology Department, 276 Bicentennial Way
Middlebury, Vermont 05753 USA
Phone: 1-802-443-2557 -- FAX: 1-802-443-2072
My research interests are in the areas of surficial geology and low-temperature mineralogy/geochemistry, especially as applied to bedrock aquifers, tropical soils and sedimentary rocks. Research methods include field work, X-ray diffraction, scanning electron microscopy, ICP-MS and other complementary methods of major and trace element analysis. I also wrote a textboox (Environmental and Low-Temperature Geochemistry) that was published in 2014 by Wiley. An errata sheet is availabe here pdf
Ryan, P.C., West, D.P., Hattori, K., Studwell, S.*, Allen, D., Kim, J., 2015. The influence of metamorphic grade on arsenic in metasedimentary bedrock aquifers: A case study from western New England, USA. Science of the Total Environment 505, 1320–1330. http://dx.doi.org/10.1016/j.scitotenv.2014.05.021. pdf
Kim, J., Ryan, P.C., Klepeis, K., Gleeson, T., North, K.*, Bean, J.*, Davis, L.*, Filoon, J.*, 2014. Ordovician thrust fault controls hydrogeology and geochemistry of a bedrock aquifer system in NW Vermont: northeastern Appalachian foreland. Geofluids 14, 266-290. DOI: 10.1111/gfl.12076. pdf
Ryan P.C., Huertas, F.J., 2013. Reaction pathways of clay minerals in tropical soils: insights from kaolinite-smectite synthesis experiments. Clays and Clay Minerals 61, 303-318. pdf
Ryan, P.C., Kim, J.J., Mango, H., Hattori, K., Thompson, A.*, 2013. Arsenic in a fractured slate aquifer system, New England (USA): Influence of bedrock geochemistry, groundwater flow paths, redox and ion exchange. Applied Geochemistry 39, 181-192. doi: http://dx.doi.org/10.1016/j.apgeochem.2013.09.010. pdf
Ryan P.C., Kim J, Wall A.J., Moen, J.C.*, Corenthal, L.G.*, Chow, D.R.*, Sullivan, C.M.*, Bright, K.*, 2011. Ultramafic-derived arsenic in a fractured bedrock aquifer. Applied Geochemistry 26, 444-457. pdf
Ryan P.C., Huertas, F.J., 2009. The temporal evolution of pedogenic Fe-smectite to Fe-kaolin via interstratified kaolin-smectite in a moist tropical soil chronosequence. Geoderma 151, 1-15. pdf
Ryan P.C., Hillier S., Wall A.J.*, 2008, Stepwise effects of the BCR sequential chemical extraction procedure on dissolution and metal release from common ferromagnesian clay minerals: a combined solution chemistry and X-ray powder diffraction study. Science of the Total Environment 407, 603-614. pdf
Munroe J.S., Ryan P.C., Carlson H.A.*, and Miller E.K., 2008, Testing Latest Wisconsinan Ice Flow Directions in Vermont through Quantitative X-ray Diffraction Analysis of Soil Mineralogy. Northeastern Geology and Environmental Sciences, 29(4): 263-275. pdf
Munroe JS, Farrugia G*, Ryan PC. 2007. Parent material and chemical weathering in alpine soils on Mount Mansfield, Vermont, USA. Catena 70(1), 39-48. pdf
Fisher GB*, Ryan PC. 2006. The smectite to disordered kaolinite transition in a tropical soil chronosequence, Pacific Coast, Costa Rica. Clays & Clay Minerals 54, 571-586. pdf
Click here for topographic map of Esterillos Terraces sample sites.
Kautz CQ*, Ryan PC. 2003. The 10 Å to 7 Å halloysite transition in a tropical soil sequence, Costa Rica. Clays and Clay Minerals 51, 252-263. pdf
Sears JW, Ryan PC. 2003. Cenozoic evolution of the Montana Cordillera: evidence from paleovalleys. Cenozoic Systems of the Rocky Mountain Region (Raynolds RG, Flores RM, Eds.), SEPM Special Publication, Denver, CO. pdf
Ryan PC, Wall AJ*, Hillier S, Clark L. 2002. Insights into sequential chemical extraction from quantitative XRD: A study of trace metal partitioning in sediments related to frog malformities. Chemical Geology 184, 337-357. pdf
Ryan PC, Hillier S. 2002. Facies relationships of Fe-rich clays in the Sundance Formation. American Mineralogist 87, 1607-1615. pdf
Hillier S, Ryan PC. 2002. Identification of halloysite (7Å) by ethylene glycol solvation: The MacEwan effect. Clay Minerals 37, 395-404. pdf
Ryan PC, Conrad ME, Brown K*, Chamberlain CP, Reynolds, RC Jr. 1998. Oxygen isotopic compositions of serpentine/chlorite and illite/smectite in the Tuscaloosa Formation (US Gulf Coast): Implications for pore fluids and mineralogic reactions. Clays and Clay Minerals 46, 357-368. pdf
Ryan PC, Buckley SN. 1998. Sedimentation, stratabound Cu-Ag mineralization, and syndepositional tectonics in the Revett Formation, Flathead Indian Reservation, western Montana: in The Belt Supergroup, Proc. Belt Symposium III, Special Pub. 112, Mont. Bur. of Mines Geol., 278-289. pdf
Ryan PC, Reynolds RC, Jr. 1997. The chemical composition of serpentine/chlorite: SEM-EDX vs. XRD determinations, implications for mineralogic reactions, and the origin of anatase. Clays and Clay Minerals 45, 339-352. pdf
Ryan PC, Reynolds RC, Jr. 1996. The origin and diagenesis of grain-coating serpentine/chlorite in Tuscaloosa Formation sandstone, U.S. Gulf Coast. American Mineralogist 81, 213-225. pdf
Moe JA, Ryan PC, Elliott WC, Reynolds RC, Jr. 1996. Petrology, chemistry, and clay mineralogy of a K-bentonite in the Proterozoic Belt Supergroup of western Montana: Journal of Sedimentary Research 66, 95-99. pdf
Buckley SN, Sears JW, Ryan PC, and Lauer D. 1994. Base-metal and PGE mineralization, sedimentation and mafic magmatism related to rifting of the Middle Proterozoic Belt Supergroup, western Montana: Northwest Geology 23 (Metallogeny of the Belt-Purcell Basin), 13-18. pdf
Thompson, A.*, Ryan, P.C., Hattori, K.H., Kim, J., 2011, Geochemical and sulfur isotope analysis of Taconic slates: implications for arsenic source and mobility in a bedrock aquifer system. Geological Society of America Abstracts with Programs, Vol. 43, No. 1, p. 106.
Rosenberg, B.*, Bigl, M.F.*, Munroe, J.S., Ryan, P.C., 2011, X-ray diffraction analysis of weathering patterns in high-elevation glacial, periglacial, and eolian sediments in northern Nevada and Utah. Geological Society of America Abstracts with Programs, Vol. 43, No. 1, p. 114.
Rosenberg, B.*, Meyer, E.E., Ryan, P.C., Eberl, D.D., 2011, K-Ar dating of illite-rich rocks in the Champlain Valley, Vermont: an investigation of post-Taconian faulting and fluid flow. Geological Society of America Abstracts with Programs, Vol. 43, No. 1, p. 151.
Brooks, E.*, Kim, J., Ryan, P.C., 2011, Geochemical analysis of groundwater quality in the fractured bedrock aquifer of the town of Craftsbury, NE Vermont. Geological Society of America Abstracts with Programs, Vol. 43, No. 1, p. 107.
Mango, J., Ryan, P.C., 2011, Pyrite as the source of groundwater arsenic in Taconic slates, southwestern Vermont. Geological Society of America Abstracts with Programs, Vol. 43, No. 1, p. 135.
Ryan, P.C., Moen, J.C.*, Corenthal, L.G.*, Chow, D.R.*, Kim, J., 2010, Tetrahedral arsenic (As+5) in antigorite: Geological origin and implications for groundwater quality: SEA-CSSJ-CMS Trilateral Meeting on Clays, Spain, June 2010.
Clark, Arthur*, Smith, Taylor*, Kim, Jon, Ryan, Peter C., Mango, Helen, 2010, Elevated arsenic in domestic wells from the Taconic allochthons in southern Vermont. Geological Society of America Abstracts with Programs, Vol. 42, No. 1, p. 185.
Corenthal, Lilly*, Ryan, Peter C., Kim, Jon, 2010, Arsenic in groundwater wells in glacial drift, north-central Vermont. Geological Society of America Abstracts with Programs, Vol. 42, No. 1, p. 122.
Moen, Jonathan*, Ryan, Peter C., Kim, Jon, 2010, Analysis of arsenic speciation in ultramafic rocks by sequential chemical extraction: implications for Taconian fluid source and modern aquifer contamination. Geological Society of America Abstracts with Programs, Vol. 42, No. 1, p. 122.
Ryan, P.C., Kim, J., Clark, A.L.*, Smith, T.T.*, Chow, D.*, Sullivan, C., Bright, K., 2009, Ultramafic source of arsenic in a fractured bedrock aquifer. Geological Society of America Abstracts with Programs, Vol. 41, No. 7, p. 218.
Ryan, P.C. and Huertas, F.J., 2009, The origin of Fe-kaolin from precursor beidellite and interstratified kaolin-smectite in moist tropical soils. Programs and Abstracts, 14th International Clay Conference, Castellaneta, Italy, June 2009.
Ryan, P.C. and Huertas, F.J., 2009, Insights into the transformation of ferruginous beidellite to K-S and kaolin from synthesis experiments. Programs and Abstracts, 14th International Clay Conference, Castellaneta, Italy, June 2009.
Kim, J., Ryan, P., North, K.*, Bean, J.*, and Davis, L., 2009, Radionuclides, groundwater geochemistry, and hydrogeology above, below, and through the Hinesburg thrust: NW Vermont. Geological Society of America Abstracts with Programs, V. 41, n. 3, p. 21.
Ryan, P.C., Kim, J., Chow, D.*, Sullivan, C., and Bright, K., 2009, Connection between Ordovician mantle metasomatism and arsenic in Vermont groundwater. Geological Society of America Abstracts with Programs, V. 41, n. 3, p. 8.
Brachfeld, S., Manley, P., Gorring, M., and Ryan, P., 2007, Contributions of Sediment Provenance and Sediment Diagenesis to Western Antarctic Peninsula Magnetic Proxy Records. American Geophysical Union, Fall Meeting 2007, abstract #GP21B-04.
Gleason, Michael J.*, Kim, Jonathan, Coish, Raymond and Ryan, Peter C, (2007) Radionuclide-enriched groundwater, Knox Mountain pluton, Vermont: occurrence and lithologic controls, Geological Society of America Abstracts with Programs, v. 39, n. 1, p. 102.
Ryan, Peter C., Coish, Ray, and Joseph*, Kristiaan (2007), Ordovician K-Bentonites in western Vermont : mineralogic, stratigraphic and geochemical evidence for their occurrence and tectonic significance, Geological Society of America Abstracts with Programs, v. 39, n. 1, p. 50.
Sullivan, Colleen*, Bright, Kevin*, Kim, Jonathan, and Ryan, Peter C. (2007) Potential ultramafic-derived arsenic contamination in bedrock water wells in north-central Vermont, Geological Society of America Abstracts with Programs, v. 39, n. 1, p. 71.
North KP*, Kim J, Ryan P. 2005. Evaluation of geologic controls on elevated naturally-occurring radioactivity in bedrock ground water wells, NW Vermont. Geological Society of America 37 (1), 78.
Fisher GB*, Ryan PC. 2005. The ferruginous beidellite to halloysite transition in a tropical soil chronosequence. Clay Minerals Society 43rd Annual Meeting, 41. ** This paper won best student presentation at the meeting.
Cowden S*, Ryan PC, Greenglass N*. 2004. Lead in groundwater derived from a fractured carbonate aquifer (Clarendon Springs Formation), northwestern Vermont. Geological Society of America 36 (2), 66.
Ryan P, Hillier S, Wall A*, Wesolowski M*. 2004. Serpentinite weathering and trace metal mobility in dry tropical forest (NW Costa Rica) and cool temporate grassland (SW England). Geological Society of America 36 (5), 27.
Fisher GB*, Ryan PC. 2004. Clay mineral weathering sequence in a tropical terrace progression, Costa Rica. Geological Society of America 36 (2), 73.
Ryan PC, Hillier S, Wall AJ*. 2003. Trace metal speciation in soils derived from ultramafic rock, northwestern Costa Rica. Geological Society of America 34 (7), 241.
Cook R*, Ryan PC, Miller EK. 2003. Spatial variability in exchangeable calcium concentrations in Vermont spodosols. Geological Society of America 34 (7), 406.
Ryan PC, Hillier S. 2002. Berthierine-chamosite, corrensite and discrete chlorite from evolved verdine and evaporite-associated facies in the Jurassic Sundance Formation, Wyoming, USA. Prog. Abs., Clay Minerals Society, 39th Annual Mtg, Boulder, CO, p. 149.
Cook RC, Ryan PC, 2002. Differentiation of two Quaternary lahars by clay mineralogical, quantitative X-ray diffraction and particle size analyses. GSA Abstracts with Programs v. 34 (5), p. A28. ** This presentation won the best student poster award.
Kautz CQ*, Ryan PC. 2002. The mineralogical record of climate change in the John Day Formation, central Oregon. GSA Abstracts with Programs v. 34 (5), p. A26
Parris A, Bosley A, Noren A, Bierman P, Lini A, Ryan P. 2002. Holocene flood frequency in New England: Large, episodic events in the sediment record. GSA Abstracts with Programs v. 34.
Carlson HA*, Ryan PC. 2001. Quantitative XRD analysis of spodosols as a means of assessing response to acid deposition. GSA Abstracts with Programs v. 33, p. A362.
Kautz CQ*, Ryan PC. 2001. Formation of multiple halloysitic phases in a neotropical fluvial terrace Sequence. GSA Abstracts with Programs v. 33, p. A437.
Ryan PC, Hillier S. 2001. Paleoenvironmental significance of Fe-Mg clays in sandstones. GSA Abstracts with Programs v. 33, p. A73.
Ryan PC, Kautz CQ*. 2001. Formation of multiple halloysitic phases in a neotropical fluvial terrace sequence. Prog. Abs., Clay Minerals Society, 38th Annual Mtg, Madison, WI, p. 73.
Sullivan MY*, Ryan PC. 2001. Geochemical analysis of sediments in the Ompompanoosuc River near the Elizabeth Mine, South Strafford, Vermont. Geol Soc. America 33 (1).
Nichols D*, Ryan PC. 2001. Hydrothermal origin of Kaolinite at Brandon and Monkton, Vermont. Geol Soc. America 33 (1).