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...
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 J.; Williams, Michael L.; Chiarenzelli, Jeffrey R.; Toft, Megan E.; McAleer, Ryan A transect through Vermont’s most famous volcano – Mount Ascutney: GSNH Summer 2017 Field Trip
No abstract available.
Walsh, Gregory J. 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 J.; 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 J. 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 J. Geochemistry and origin of metamorphosed mafic rocks from the Lower Paleozoic Moretown and Cram Hill Formations of North-Central Vermont: Delamination magmatism in the western New England appalachians
The Moretown Formation, exposed as a north-trending unit that extends from northern Vermont to Connecticut, is located along a critical Appalachian litho-tectonic zone between the paleomargin of Laurentia and accreted oceanic terranes. Remnants of magmatic activity, in part preserved as metamorphosed mafic rocks in the Moretown Formation and the...
Coish, Raymond; Kim, Jonathan; Twelker, Evan; Zolkos, Scott P.; Walsh, Gregory J.
Bedrock geologic map of the Worcester South quadrangle, Worcester County, Massachusetts
The bedrock geology of the 7.5-minute Worcester South quadrangle, Massachusetts, consists of deformed Neoproterozoic to Paleozoic crystalline metamorphic and intrusive igneous rocks in three fault-bounded terranes (zones), including the Avalon, Nashoba, and Merrimack zones (Zen and others, 1983). This quadrangle spans the easternmost occurrence of...
Walsh, Gregory J.; Merschat, Arthur J. Neoproterozoic–Cambrian stratigraphic framework of the Anti-Atlas and Ouzellagh promontory (High Atlas), Morocco
In the last two decades, great progress has been made in the geochronological, chrono- and chemostratigraphic control of the Neoproterozoic and Cambrian from the Anti-Atlas Ranges and the Ouzellagh promontory (High Atlas). As a result, the Neoproterozoic is lithostratigraphically subdivided into: (i) the Lkest-Taghdout Group (broadly interpreted...
Alvaro, Jose Javier; Benziane, Fouad; Thomas, Robert; Walsh, Gregory J.; Yazidi, Abdelaziz
Bedrock geologic map of the Uxbridge quadrangle, Worcester County, Massachusetts, and Providence County, Rhode Island
The bedrock geology of the 7.5-minute Uxbridge quadrangle consists of Neoproterozoic metamorphic and igneous rocks of the Avalon zone. In this area, rocks of the Avalon zone lie within the core of the Milford antiform, south and east of the terrane-bounding Bloody Bluff fault zone. Permian pegmatite dikes and quartz veins occur throughout the...
Walsh, Gregory J.
Bedrock geologic map of the Nashua South quadrangle, Hillsborough County, New Hampshire, and Middlesex County, Massachusetts
The bedrock geology of the 7.5-minute Nashua South quadrangle consists primarily of deformed Silurian metasedimentary rocks of the Berwick Formation. The metasedimentary rocks are intruded by a Late Silurian to Early Devonian diorite-gabbro suite, Devonian rocks of the Ayer Granodiorite, Devonian granitic rocks of the New Hampshire Plutonic Suite...
Walsh, Gregory J.; Jahns, Richard H.; Aleinikoff, John N. A 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 (...
Thompson, Thelma Barton; Thompson, Peter J.; Walsh, Gregory J.; Valley, Peter M.; Sicard, Karri R. Neoproterozoic tectonic evolution of the Jebel Saghro and Bou Azzer - El Graara inliers, eastern and central Anti-Atlas, Morocco
New mapping, geochemistry, and 17 U–Pb SHRIMP zircon ages from rocks of the Sirwa, Bou Azzer–El Graara, and Jebel Saghro inliers constrain the Neoproterozoic evolution of the eastern Anti-Atlas during Pan-African orogenesis. In the Sirwa inlier, Tonian quartzite from the pre Pan-African passive margin deposits of the Mimount Formation contains...
Walsh, Gregory J.; Aleinikoff, John N.; Harrison, Richard W.; Burton, William C.; Quick, James E.; Benziane, Foudad; Yazidi, Abdelaziz; Saadane, Abderrahim