Gregory Walsh
I am a Project Chief and a Research Geologist with the Florence Bascom Geoscience Center. I manage bedrock geologic mapping activities for the USGS in the northeastern United States. I managed two international mapping projects in Morocco, the completion of the new bedrock geologic map of Vermont, and I conducted mapping Madagascar.
Biography
I have expertise in geologic mapping, structural geology, 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. I have trained students and geologists in geologic mapping, GIS, GPS, digital mapping, and U-Pb geochronology by SHRIMP.
Awards:
- Undergraduate Dean’s List five semesters (1982-1986)
- Amoco Geophysics Award (1985)
- NAGT – USGS Student Internship (1985)
- L.R. Wilson Award, UMASS Amherst (1986)
- Charles G. Doll Award, Vermont Geological Society (1988)
- Seventeen USGS performance awards (1997-2018)
- Elected GSA Fellow (2013)
View current CV HERE
Science and Products
Northeast Bedrock Mapping Project
The Northeast Bedrock Mapping Project consists of scientists conducting geologic mapping and scientific research of complexly deformed crystalline igneous and metamorphic rocks in the Northeastern United States. Current mapping activities are focused in New Hampshire, Vermont, Connecticut, and New York. The Project produces high-quality, multi-purpose digital geologic maps and accompanying...
Integrated geophysical imaging of rare-earth-element-bearing iron oxide-apatite deposits in the eastern Adirondack Highlands, New York
The eastern Adirondack Highlands of northern New York host dozens of iron oxide-apatite (IOA) deposits containing magnetite and rare earth element (REE)-bearing apatite. We use new aeromagnetic, aeroradiometric, ground gravity, and sample petrophysical and geochemical data to image and understand these deposits and their geologic framework....
Shah, Anjana K.; Taylor, Ryan D.; Walsh, Gregory; Phillips, Jeffrey
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...
Walsh, Gregory; Valley, Peter M.; Armstrong, Thomas R.; Ratcliffe, Nicholas M.; Merschat, Arthur J.; Gentry, Beau J. Photoluminescence imaging of whole zircon grains on a petrographic microscope—An underused aide for geochronologic studies
The refractory nature of zircon to temperature and pressure allows even a single zircon grain to preserve a rich history of magmatic, metamorphic, and hydrothermal processes. Isotopic dating of micro-domains exposed in cross-sections of zircon grains allows us to interrogate this history. Unfortunately, our ability to select the zircon grains in a...
McAleer, Ryan J.; Jubb, Aaron M.; Hackley, Paul C.; Walsh, Gregory; Merschat, Arthur J.; Regan, Sean P.; Burton, William C.; Vazquez, Jorge A.
Bedrock 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...
Walsh, Gregory; Valley, Peter M.; Thompson, Peter J.; Ratcliffe, Nicholas M.; Proctor, Brooks P.; Sicard, Karri R. A 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...
Walsh, Gregory; Proctor, Brooks P.; Sicard, Karri R.; Valley, Peter M. 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...
Valley, Peter M.; Walsh, Gregory; Merschat, Arthur J.; McAleer, Ryan J. Geochemistry and geophysics of iron oxide-apatite deposits and associated waste piles with implications for potential rare earth element resources from ore and historic mine waste in the eastern Adirondack Highlands, New York, USA
The iron oxide-apatite (IOA) deposits of the eastern Adirondack Highlands, New York, are historical high-grade magnetite mines that contain variable concentrations of rare earth element (REE)-bearing apatite crystals. The majority of the deposits are hosted within sodically altered Lyon Mountain granite gneiss, although some deposits occur within...
Taylor, Ryan; Shah, Anjana K.; Walsh, Gregory; Taylor, Cliff D. Syn-collisional exhumation of hot middle crust in the Adirondack Mountains (New York, USA): Implications for extensional orogenesis in the southern Grenville province
Extensional deformation in the lower to middle continental crust is increasingly recognized and shown to have significant impact on crustal architecture, magma emplacement, fluid flow, and ore deposits. Application of the concept of extensional strain to ancient orogenic systems, like the Grenville province of eastern North America, has helped...
Regan, Sean; Walsh, Gregory; Williams, Michael L.; Chiarenzelli, Jeffrey R.; Toft, Megan E.; McAleer, Ryan J. A transect through Vermont’s most famous volcano – Mount Ascutney: GSNH Summer 2017 Field Trip
No abstract available.
Walsh, Gregory Reaction softening by dissolution–precipitation creep in a retrograde greenschist facies ductile shear zone, New Hampshire, USA
We describe strain localization by a mixed process of reaction and microstructural softening in a lower greenschist facies ductile fault zone that transposes and replaces middle to upper amphibolite facies fabrics and mineral assemblages in the host schist of the Littleton Formation near Claremont, New Hampshire. Here, Na-poor muscovite and...
McAleer, Ryan J.; Bish, David L.; Kunk, Michael J.; Sicard, Karri R.; Valley, Peter M.; Walsh, Gregory; Wathen, Bryan A.; Wintsch, R. P.
Bedrock geologic map of the Hartland and North Hartland quadrangles, Windsor County, Vermont, and Sullivan and Grafton Counties, New Hampshire
The bedrock geology of the 7.5-minute Hartland and North Hartland quadrangles, Vermont-New Hampshire, consists of highly deformed and metamorphosed lower Paleozoic metasedimentary, metavolcanic, and metaplutonic rocks of the Bronson Hill anticlinorium (BHA) and the Connecticut Valley trough (CVT). Rocks of the Orfordville anticlinorium on this map...
Walsh, Gregory Identification of groundwater nitrate contamination from explosives used in road construction: Isotopic, chemical, and hydrologic evidence
Explosives used in construction have been implicated as sources of NO3– contamination in groundwater, but direct forensic evidence is limited. Identification of blasting-related NO3– can be complicated by other NO3– sources, including agriculture and wastewater disposal, and by hydrogeologic factors affecting NO3...
Degnan, James R.; Böhlke, John Karl; Pelham, Krystle; David M. Langlais; Walsh, Gregory