I have expertise in geologic mapping, igneous and metamorphic petrology, geochemistry, isotope geochronology, tectonics, digital cartography, and GIS. I specialize in the mapping, structure, and tectonics of complexly deformed rocks, the integration of geologic data with hydrogeologic and mineral resource assessment studies, and the use of GIS as a mapping and analysis tool.
Current Research
I am a research geologist with the Florence Bascom Geoscience Center. I am currently working on a bedrock mapping project in the northeastern Adirondack Mountains of New York. This project is part of a multidisciplinary study to understand the origin of magnetite-apatite ore deposits. Some of the deposits contain significant quantities of rare earth elements, which are considered critical minerals by the US government.
Professional Experience
Research Geologist, U.S. Geological Survey (Current)
Visiting Assistant Professor, State University of New York at Potsdam (2016–2017)
Sedimentologist/Petrologist, Weatherford Labs (2013-2016)
Field Geologist/Mapping, U.S. Geological Survey (2011-2013)
Field Geologist/Mapping, Geological Survey of Newfoundland and Labrador (2009-2011)
Research Scientist/Lab Manager, University of North Carolina at Chapel Hill (2004)
Adjunct Professor, Laramie County Community College (2003)
Research Technician, University of Wyoming (2001-2003)
Research Assistant, State University of New York at Buffalo (1999)
Education and Certifications
Ph.D. Geology, Memorial University of Newfoundland, 2011
M.S. Geology, University of Minnesota, 2001
B.S. Geology, Castelton State College, 1999
National Freshman Honors Society (1995)
Affiliations and Memberships*
American Association of Petroleum Geologists
Geological Association of Canada
Geological Society of America
Mineralogical Society of America
Honors and Awards
Distinction Award, PhD comprehensive exam (2005)
Summer Field Grant, University of Minnesota (2000)
Summa Cum Laude, Castleton State College (1999)
Presidential Scholarship Award, Castleton State College (1999)
Science Department Achievement Award, Castleton State College (1998)
Science and Products
Unmixing multiple metamorphic muscovite age populations with powder X-ray diffraction and 40Ar/39Ar analysis
A transect through Vermont's most famous volcano - Mount Ascutney
Geochronology of the Oliverian Plutonic Suite and the Ammonoosuc Volcanics in the Bronson Hill arc: Western New Hampshire, USA
U-Pb zircon geochronology by sensitive high-resolution ion microprobe–reverse geometry (SHRIMP-RG) on 11 plutonic rocks and two volcanic rocks from the Bronson Hill arc in western New Hampshire yielded Early to Late Ordovician ages ranging from 475 to 445 Ma. Ages from Oliverian Plutonic Suite rocks that intrude a largely mafic lower section of the Ammonoosuc Volcanics ranged from 474.8 ± 5.2 to 4
A transect through the base of the Bronson Hill Terrane in western New Hampshire
Bedrock geologic map of the Springfield 7.5- x 15-minute quadrangle, Windsor County, Vermont, and Sullivan County, New Hampshire
Bedrock geologic map of the Mount Ascutney 7.5- x 15-minute quadrangle, Windsor County, Vermont, and Sullivan County, New Hampshire
Science and Products
- Publications
Unmixing multiple metamorphic muscovite age populations with powder X-ray diffraction and 40Ar/39Ar analysis
A combination of modal estimates from powder X-ray diffraction (XRD) experiments and argon isotopic data shows that muscovite 40Ar/39Ar total gas age correlates with muscovite composition near the retrograde Bald Mountain shear zone (BMSZ) in Claremont, New Hampshire, and that the shear zone was active at ∼245 Ma. Petrologic study demonstrates that chemical disequilibrium is preserved in muscoviteAuthorsRyan J. McAleer, David Bish, Michael J. Kunk, Peter M. Valley, Gregory J. Walsh, Robert WintschA transect through Vermont's most famous volcano - Mount Ascutney
The Cretaceous Ascutney Mountain igneous complex affords a classic exposure of the White Mountain Igneous Suite. Often called Vermont’s most famous volcano, Mount Ascutney (elev. 3,144 feet, 958 m) stands as a prominent monadnock in the Connecticut River Valley. The mountain often serves as an inspirational landmark, as it does when viewed from locations throughout the valley including the Saint-AuthorsGregory J. Walsh, Brooks P. Proctor, Karri R. Sicard, Peter M. ValleyGeochronology of the Oliverian Plutonic Suite and the Ammonoosuc Volcanics in the Bronson Hill arc: Western New Hampshire, USA
U-Pb zircon geochronology by sensitive high-resolution ion microprobe–reverse geometry (SHRIMP-RG) on 11 plutonic rocks and two volcanic rocks from the Bronson Hill arc in western New Hampshire yielded Early to Late Ordovician ages ranging from 475 to 445 Ma. Ages from Oliverian Plutonic Suite rocks that intrude a largely mafic lower section of the Ammonoosuc Volcanics ranged from 474.8 ± 5.2 to 4
AuthorsPeter M. Valley, Gregory J. Walsh, Arthur J. Merschat, Ryan J. McAleerA transect through the base of the Bronson Hill Terrane in western New Hampshire
This trip will present the preliminary results of ongoing bedrock mapping in the North Hartland and Claremont North 7.5-minute quadrangles in western New Hampshire. The trip will travel from the Lebanon pluton to just north of the Sugar River pluton (Fig. 1) with the aim of examining the lower structural levels of the Bronson Hill anticlinorium (BHA), and the nature of the boundary with the rocksAuthorsGregory J. Walsh, Peter M. Valley, Karri R. Sicard - Maps
Bedrock geologic map of the Springfield 7.5- x 15-minute quadrangle, Windsor County, Vermont, and Sullivan County, New Hampshire
The bedrock geology of the 7.5- by 15-minute Springfield quadrangle consists of highly deformed and metamorphosed Mesoproterozoic through Devonian metasedimentary and meta-igneous rocks. In the west, Mesoproterozoic gneisses of the Mount Holly Complex are the oldest rocks and form the eastern side of the Chester dome. The Moretown slice structurally overlies the Chester dome along the Keyes MountaBedrock geologic map of the Mount Ascutney 7.5- x 15-minute quadrangle, Windsor County, Vermont, and Sullivan County, New Hampshire
The bedrock geology of the Mount Ascutney 7.5- x 15-minute quadrangle consists of highly deformed and metamorphosed Mesoproterozoic through Devonian metasedimentary and meta-igneous rocks intruded by rocks of the Mesozoic White Mountain Igneous Suite. In the west, Mesoproterozoic gneisses of the Mount Holly Complex are the oldest rocks and form the northeastern flank of the Chester dome. The alloc
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government