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Gregory Walsh

I am a Project Leader and a Supervisory 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.

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. The Publications listed on the tab below is automatically generated and incomplete. Please contact me if you would like a copy of my current CV.

Professional Experience

  • 1992-Present, Research Geologist, U.S. Geological Survey, Reston, Virginia and Montpelier, Vermont

  • 1990-1992, Consulting Geologist, Heindel and Noyes, Inc., Burlington, Vermont

  • 1988-1990, Contractor, Vermont Agency of Natural Resources, Waterbury, Vermont

  • 1986-1988, Teaching Assistant, University of Vermont, Department of Geology, Burlington, Vermont

  • 1986, NAGT Intern Geologist, U.S. Geological Survey, Menlo Park, California

Education and Certifications

  • M.S. in Geology / University of Vermont, Burlington, Vermont USA, 1989

  • B.S. in Geology / University of Massachusetts, Amherst, Massachusetts, 1986

Affiliations and Memberships*

  • 2013-Present, Fellow, Geological Society of America

  • 1988-2013, Member, Geological Society of America

  • 2013-2014, Elected Vice-Chair, Geological Society of America, Northeastern Section Management Board

  • 2014-2015, Chair, Geological Society of America, Northeastern Section Management Board

  • 2015-2016, Past-Chair, Geological Society of America, Northeastern Section Management Board

  • 2012-Present, Member, Connecticut Geological Society

  • 1998-Present, Member, New Hampshire Geological Society

  • 1992-Present, Member, Vermont Geological Society

Honors and Awards

  • 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)

  • Twenty-one USGS performance awards (1997-2021)

  • Elected GSA Fellow (2013)

Science and Products

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A view of Mount Ascutney, the Connecticut River, and the Cornish-Windsor Covered Bridge.

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...
By
Florence Bascom Geoscience Center, Geology, Geophysics, and Geochemistry Science Center
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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...
Learn More

Generalized lithology for lithogeochemical classification of the bedrock of Vermont

This data release provides a generalized lithology look-up table for the lithogeochemical classification of Vermont's bedrock geologic map units. The table is defined from the mapped bedrock geologic units published by Ratcliffe and others (2011) and the generalized lithology of rock group A and rock group B for lithogeochemical classification as defined by Robinson and Kapo (2003). The 2003 class
By
Florence Bascom Geoscience Center

Whole rock geochemistry data from the Ordovician Bronson Hill arc and Silurian and Devonian Connecticut Valley - Gaspé trough, Vermont and New Hampshire

This data release includes whole rock (WR) geochemical data for 94 samples. Whole rock geochemistry data were analyzed at Actlabs in Ancaster, Ontario, Canada. Rock samples were collected by Peter Valley, Greg Walsh, Arthur Merschat, and Ryan McAleer. The whole rock geochemistry data characterize the composition of mapped meta-igneous rocks in eastern Vermont and western New Hampshire, USA. The da
By
Florence Bascom Geoscience Center

Database of historical anthracite coal-mining infrastructure at the northern end of the Lackawanna syncline, Wayne, Susquehanna, and Lackawanna counties, Pennsylvania

Abandoned railroads and infrastructure from the anthracite coal mining industry are significant features in abandoned mine lands and are an important part of history; however, these features are often lost and masked by the passage of time and the regrowth of forests. The application of modern light detection and ranging (lidar) topographic analysis, combined with ground-truthing "boots on the gro
By
Florence Bascom Geoscience Center

Whole rock geochemistry and uranium-lead isotopic data from Mesoproterozoic rocks in the Eagle Lake quadrangle, Essex County, New York

This data release includes whole rock (WR) geochemical data, and uranium-lead isotopic data collected using a sensitive high resolution ion microprobe-reverse geometry (SHRIMP-RG) instrument; the SHRIMP-RG is a type of secondary ion mass spectrometer (SIMS). Whole rock geochemistry data were analyzed at Bureau Veritas Commodities Canada Ltd. Laboratories in Vancouver, British Columbia, Canada. SHR
By
Florence Bascom Geoscience Center

Electron microprobe and 40Ar/39Ar isotopic data from west-central New Hampshire

This dataset accompanies planned publication 'Unmixing multiple metamorphic muscovite age populations with powder X-ray diffraction and 40Ar/39Ar analysis'. The 40Ar/39Ar and electron microprobe data are from samples adjacent to a lower greenschist facies shear zone in western New Hampshire. The geochronology coupled with the electron microprobe data provide a petrochronologic framework for the ro
By
Florence Bascom Geoscience Center

Data release for depth to bedrock from Connecticut Water Resources Bulletins

This data release consists of information from published tables in Connecticut Water Resources Bulletins (WRBs) transcribed into tabular digital format. Information about wells and test holes in the WRBs used in this data release consists of geographic location, depth to consolidated rock (bedrock depth), and depth of the well or test hole. The WRBs, published between 1966 and 1980 by the U.S. Geo
By
Florence Bascom Geoscience Center

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 heavy mineral concentrate that records the most ge
By
Florence Bascom Geoscience Center, Bascom ARgon Dating (BARD) Laboratory

Electron microprobe analyses of feldspars and petrographic, geochemical, and geochronologic data from the Hawkeye Granite Gneiss and Lyon Mountain Granite Gneiss in the Adirondacks of New York (ver. 2.0, May 2023)

Iron oxide-apatite (IOA) deposits of the Adirondack Mountains of New York locally contain elevated rare earth element (REE) concentrations (e.g. Taylor and others, 2019). Critical to evaluating resource potential is understanding the genesis of the IOA deposits that host the REE-rich minerals. As part of this effort, the U.S. Geological Survey (USGS) is conducting bedrock geologic mapping, geoch
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Florence Bascom Geoscience Center, Bascom ARgon Dating (BARD) Laboratory

Petrophysical data collected on outcrops and rock samples from the eastern Adirondack Highlands, New York

Petrophysical data were collected in the eastern Adirondack Highlands during several field campaigns in 2016-2017. This data release provides magnetic susceptibility, gamma spectrometry, and density measurements on rock outcrops, hand samples, and during walking surveys. Rock types for the outcrops and samples were identified using standard field methods. Locations of the outcrops or samples were
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Geology, Geophysics, and Geochemistry Science Center

GIS and Data Tables for Focus Areas for Potential Domestic Nonfuel Sources of Rare Earth Elements

In response to Executive Order 13817 of December 20, 2017, the U.S. Geological Survey (USGS) coordinated with the Bureau of Land Management (BLM) to identify 35 nonfuel minerals or mineral materials considered critical to the economic and national security of the United States (U.S.). Acquiring information on possible domestic sources of these critical minerals is the basis of the USGS Earth Mappi
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Earth Mapping Resources Initiative (Earth MRI)

Geochemistry of ore, host rock, and mine waste pile samples of iron oxide-apatite (IOA) deposits of the eastern Adirondack Highlands, New York, in relation to potential rare earth elements resources, 2016-2018

Thirty-four ore, twenty-nine mine waste, seven host rock, two pegmatite, and one slag sample were collected from iron oxide-apatite (IOA) mines in the eastern Adirondack Highlands near Mineville and Ticonderoga, New York, from March 2016 to August 2018. The waste pile samples included twenty-five samples collected from rubble-sized mine waste piles and four samples from processed tailings piles.
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center
Filter Total Items: 14

Bedrock geologic map of the Woodstock quadrangle, Grafton County, New Hampshire

The bedrock geology of the Woodstock 7.5-minute quadrangle consists of highly deformed metasedimentary rocks of the Central Maine trough, including the Silurian Rangeley and Perry Mountain Formations and the Devonian Littleton Formation. The central, northern, and eastern parts of the quadrangle are underlain by the oldest rocks in the area, the Rangeley Formation. In the southwest and south-centr
By
Florence Bascom Geoscience Center

Percent-slope map showing historical anthracite coal-mining infrastructure at the northern end of the Lackawanna syncline, Wayne, Susquehanna, and Lackawanna Counties, Pennsylvania

Introduction Abandoned railroads and infrastructure from the anthracite coal-mining industry are significant features in abandoned mine lands and are an important part of history; however, these features are often lost and masked by the passage of time and the regrowth of forests. The application of modern light detection and ranging (lidar) topographic analysis, combined with field verification,
By
Florence Bascom Geoscience Center

Bedrock geologic map of the Crown Point quadrangle, Essex County, New York, and Addison County, Vermont

The bedrock geology of the 7.5-minute Crown Point quadrangle consists of deformed and metamorphosed Mesoproterozoic gneisses of the Adirondack Highlands unconformably overlain by weakly deformed lower Paleozoic sedimentary rocks of the Champlain Valley. The Mesoproterozoic rocks occur on the eastern edge of the Adirondack Highlands and represent an extension of the Grenville Province of Laurentia.
By
Florence Bascom Geoscience Center

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 Mounta
By
Florence Bascom Geoscience Center

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 the northeastern flank of the Chester dome. The alloc
By
Florence Bascom Geoscience Center

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 occupy the western part of the broader BHA. In the
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Florence Bascom Geoscience Center

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 Ganderian margin arc-related rocks (Nashoba zone)
By
Florence Bascom Geoscience Center

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 quadrangle. The oldest metasedimentary rocks include th
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Florence Bascom Geoscience Center

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 including pegmatite and the Chelmsford Granite, and
By
Florence Bascom Geoscience Center

Bedrock geologic map of Vermont

The Bedrock Geologic Map of Vermont is the result of a cooperative agreement between the U.S. Geological Survey (USGS) and the State of Vermont. The State's complex geology spans 1.4 billion years of Earth's history. The new map comes 50 years after the most recent map of the State by Charles G. Doll and others in 1961 and a full 150 years since the publication of the first geologic map of Vermont

Bedrock geologic map of the Grafton quadrangle, Worcester County, Massachusetts

The bedrock geology of the 7.5-minute Grafton, Massachusetts, quadrangle consists of deformed Neoproterozoic to early Paleozoic crystalline metamorphic and intrusive igneous rocks. Neoproterozoic intrusive, metasedimentary, and metavolcanic rocks crop out in the Avalon zone, and Cambrian to Silurian intrusive, metasedimentary, and metavolcanic rocks crop out in the Nashoba zone. Rocks of the Avalo

Bedrock geologic map of the Montpelier and Barre West quadrangles, Washington and Orange Counties, Vermont

The bedrock geology of the Montpelier and Barre West quadrangles consists of Silurian and Devonian metasedimentary rocks of the Connecticut Valley-Gaspe synclinorium (CVGS) and metasedimentary, metavolcanic, and metaintrusive rocks of the Cambrian and Ordovician Moretown and Cram Hill Formations. Devonian granite dikes occur throughout the two quadrangles but are more abundant in the Silurian and
Hydrologic technician showing a high-water mark on a debris line next to the Black River in Ludlow VT
Hydrologic technician showing a high-water mark on a debris line
Hydrologic technician showing a high-water mark on a debris line
Hydrologic technician showing a high-water mark on a debris line next to the Black River in Ludlow VT

Hydrologic technician showing a high-water mark on a debris line

Hydrologic technician showing a high-water mark on a debris line

Hydrologic technician showing a high-water mark on a debris line next to the Black River in Ludlow Vermont.

By
New England Water Science Center, New England Water Science Center
Hydrologic technician showing a high-water mark on a debris line next to the Black River in Ludlow VT

Hydrologic technician showing a high-water mark on a debris line

Hydrologic technician showing a high-water mark on a debris line

Hydrologic technician showing a high-water mark on a debris line next to the Black River in Ludlow Vermont.

By
New England Water Science Center, New England Water Science Center
Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River
Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River
Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River
Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

 Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

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New England Water Science Center, New England Water Science Center
Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

 Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

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New England Water Science Center, New England Water Science Center
High-water mark on door at Montpelier Federal Building
High-water mark on door at Montpelier, Vermont Federal Building
High-water mark on door at Montpelier, Vermont Federal Building
High-water mark on door at Montpelier Federal Building

High-water mark on door at Montpelier, Vermont Federal Building

High-water mark on door at Montpelier, Vermont Federal Building

High-water mark on door at Montpelier, Vermont Federal Building during major flood event in July 2023.

By
New England Water Science Center
High-water mark on door at Montpelier Federal Building

High-water mark on door at Montpelier, Vermont Federal Building

High-water mark on door at Montpelier, Vermont Federal Building

High-water mark on door at Montpelier, Vermont Federal Building during major flood event in July 2023.

By
New England Water Science Center
High-water mark on door at Federal Building, Montpelier, Vermont
High-water mark on door at Federal Building, Montpelier, Vermont
High-water mark on door at Federal Building, Montpelier, Vermont
High-water mark on door at Federal Building, Montpelier, Vermont

High-water mark on door at Federal Building, Montpelier, Vermont

High-water mark on door at Federal Building, Montpelier, Vermont

High-water mark on door at Federal Building, Montpelier, Vermont during major flood event in July 2023.

By
New England Water Science Center
High-water mark on door at Federal Building, Montpelier, Vermont

High-water mark on door at Federal Building, Montpelier, Vermont

High-water mark on door at Federal Building, Montpelier, Vermont

High-water mark on door at Federal Building, Montpelier, Vermont during major flood event in July 2023.

By
New England Water Science Center
Flooded stairwell to Montpelier, Vermont Federal Building
Flooded stairwell to Montpelier, Vermont Federal Building
Flooded stairwell to Montpelier, Vermont Federal Building
Flooded stairwell to Montpelier, Vermont Federal Building

Flooded stairwell to Montpelier, Vermont Federal Building

Flooded stairwell to Montpelier, Vermont Federal Building

Flooded stairwell to Montpelier, Vermont Federal Building during historical flood event.

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New England Water Science Center, New England Water Science Center
Flooded stairwell to Montpelier, Vermont Federal Building

Flooded stairwell to Montpelier, Vermont Federal Building

Flooded stairwell to Montpelier, Vermont Federal Building

Flooded stairwell to Montpelier, Vermont Federal Building during historical flood event.

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New England Water Science Center, New England Water Science Center
A boat sits along a dock on Paradox Lake. The autumn colored trees are reflected in the placid lake.
Autumn colors reflected on Paradox Lake in the Adirondack Mountains
Autumn colors reflected on Paradox Lake in the Adirondack Mountains
A boat sits along a dock on Paradox Lake. The autumn colored trees are reflected in the placid lake.

Autumn colors reflected on Paradox Lake in the Adirondack Mountains

Autumn colors reflected on Paradox Lake in the Adirondack Mountains

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.

By
Florence Bascom Geoscience Center
A boat sits along a dock on Paradox Lake. The autumn colored trees are reflected in the placid lake.

Autumn colors reflected on Paradox Lake in the Adirondack Mountains

Autumn colors reflected on Paradox Lake in the Adirondack Mountains

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.

By
Florence Bascom Geoscience Center
Filter Total Items: 77

Implementation plan of the National Cooperative Geologic Mapping Program strategy—Northeast region of the United States: New York and New England

Complexly deformed igneous, metamorphic, and sedimentary rocks form the bedrock of the Northeast region of the United States. Variably thick unconsolidated sediments deposited by glacial, fluvial, and eolian systems locally cover the bedrock. New geologic mapping focuses on areas lacking modern, detailed studies or syntheses, and contributes to existing framework research. This report addresses pl
Authors
Gregory J. Walsh, Margaret A. Thomas, Robert G. Marvinney, Stephen B. Mabee, Frederick H. Chormann, Andrew Kozlowski, Marjorie H. Gale, Jon Kim, Brian Savage
By
Florence Bascom Geoscience Center

An apparent dip calculator for spreadsheets

This report and spreadsheet calculator contain Microsoft Excel-based equations that are useful in structural geology to calculate plunge or apparent dip when measuring lineations on a plane. The spreadsheet allows users to measure the trend or the plunge of a lineation and calculate the corresponding unknown value of trend or plunge. The spreadsheet provides the user with two options:Option 1: Cal
Authors
Gregory J. Walsh
By
Florence Bascom Geoscience Center

Age and tectonic setting of the Quinebaug-Marlboro belt and implications for the history of Ganderian crustal fragments in southeastern New England, USA

Crustal fragments underlain by high-grade rocks represent a challenge to plate reconstructions, and integrated mapping, geochronology, and geochemistry enable the unravelling of the temporal and spatial history of exotic crustal blocks. The Quinebaug-Marlboro belt (QMB) is an enigmatic fragment on the trailing edge of the peri-Gondwanan Ganderian margin of southeastern New England. SHRIMP U-Pb geo
Authors
Gregory J. Walsh, John N. Aleinikoff, Robert A. Ayuso, Robert P. Wintsch
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Geology, Energy & Minerals Science Center, Geology, Geophysics, and Geochemistry Science Center, Florence Bascom Geoscience Center

New interpretations of the ages and origins of the Hawkeye Granite Gneiss and Lyon Mountain Granite Gneiss, Adirondack Mountains, NY: Implications for the nature and timing of Mesoproterozoic plutonism, metamorphism, and deformation

The Hawkeye Granite Gneiss and Lyon Mountain Granite Gneiss are widespread Mesoproterozoic plutonic rocks that occur in the amphibolite- to granulite-facies Adirondack Highlands of northern New York, USA. The strongly deformed Hawkeye Granite Gneiss, previously dated by zircon multi-grain thermal ionization mass spectrometry (TIMS) U-Pb analyses at about 1100 Ma, was intruded by the weakly deforme
Authors
John N. Aleinikoff, Gregory J. Walsh, Ryan J. McAleer
By
Mineral Resources Program, Florence Bascom Geoscience Center, Geology, Geophysics, and Geochemistry Science Center

Renewing the National Cooperative Geologic Mapping Program as the Nation’s authoritative source for modern geologic knowledge

This document presents the renewed vision, mission, and goals for the National Cooperative Geologic Mapping Program (NCGMP). The NCGMP, as authorized by the National Cooperative Geologic Mapping Act of 1992 (Public Law 102-285, 106 Stat. 166 and its reauthorizations), is tasked with expediting the production of a geologic database for the Nation based on modern geologic maps and their supporting d
Authors
John Brock, Karen Berry, James Faulds, Richard Berg, Kyle House, Michael Marketti, Darcy McPhee, Kevin M. Schmidt, James Schmitt, David R. Soller, David Spears, Ren A. Thompson, Harvey Thorleifson, Gregory J. Walsh
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National Cooperative Geologic Mapping Program, Geosciences and Environmental Change Science Center

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 muscovite
Authors
Ryan J. McAleer, David Bish, Michael J. Kunk, Peter M. Valley, Gregory J. Walsh, Robert Wintsch
By
National Cooperative Geologic Mapping Program, Florence Bascom Geoscience Center

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. Aeromagnetic total field data reflect highly magnetic leu
Authors
Anjana K. Shah, Ryan D. Taylor, Gregory J. Walsh, Jeffrey Phillips
By
Geology, Geophysics, and Geochemistry Science Center

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 heavy mineral concentrate that records the most ge

Authors
Ryan J. McAleer, Aaron M. Jubb, Paul C. Hackley, Gregory J. Walsh, Arthur J. Merschat, Sean P. Regan, William C. Burton, Jorge A. Vazquez
By
Energy Resources Program, Volcano Hazards Program, Florence Bascom Geoscience Center, Volcano Science Center, Bascom ARgon Dating (BARD) Laboratory

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 locations throughout the valley including the Saint-
Authors
Gregory J. Walsh, Brooks P. Proctor, Karri R. Sicard, Peter M. Valley
By
Florence Bascom Geoscience Center

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

Authors
Peter M. Valley, Gregory J. Walsh, Arthur J. Merschat, Ryan J. McAleer
By
Florence Bascom Geoscience Center, Bascom ARgon Dating (BARD) Laboratory

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 paragneiss, gabbro, anorthosite, or potassically al
Authors
Ryan Taylor, Anjana K. Shah, Gregory J. Walsh, Cliff D. Taylor
By
Geology, Geophysics, and Geochemistry Science Center, Florence Bascom Geoscience Center

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 decipher the structural evolution of these regions. Th
Authors
Sean Regan, Gregory J. Walsh, Michael L. Williams, Jeffrey R. Chiarenzelli, Megan E. Toft, Ryan J. McAleer
By
Florence Bascom Geoscience Center, Bascom ARgon Dating (BARD) Laboratory, Reston Electron Microbeam Laboratory

Science and Products

link
A view of Mount Ascutney, the Connecticut River, and the Cornish-Windsor Covered Bridge.

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...
By
Florence Bascom Geoscience Center, Geology, Geophysics, and Geochemistry Science Center
link

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...
Learn More

Generalized lithology for lithogeochemical classification of the bedrock of Vermont

This data release provides a generalized lithology look-up table for the lithogeochemical classification of Vermont's bedrock geologic map units. The table is defined from the mapped bedrock geologic units published by Ratcliffe and others (2011) and the generalized lithology of rock group A and rock group B for lithogeochemical classification as defined by Robinson and Kapo (2003). The 2003 class
By
Florence Bascom Geoscience Center

Whole rock geochemistry data from the Ordovician Bronson Hill arc and Silurian and Devonian Connecticut Valley - Gaspé trough, Vermont and New Hampshire

This data release includes whole rock (WR) geochemical data for 94 samples. Whole rock geochemistry data were analyzed at Actlabs in Ancaster, Ontario, Canada. Rock samples were collected by Peter Valley, Greg Walsh, Arthur Merschat, and Ryan McAleer. The whole rock geochemistry data characterize the composition of mapped meta-igneous rocks in eastern Vermont and western New Hampshire, USA. The da
By
Florence Bascom Geoscience Center

Database of historical anthracite coal-mining infrastructure at the northern end of the Lackawanna syncline, Wayne, Susquehanna, and Lackawanna counties, Pennsylvania

Abandoned railroads and infrastructure from the anthracite coal mining industry are significant features in abandoned mine lands and are an important part of history; however, these features are often lost and masked by the passage of time and the regrowth of forests. The application of modern light detection and ranging (lidar) topographic analysis, combined with ground-truthing "boots on the gro
By
Florence Bascom Geoscience Center

Whole rock geochemistry and uranium-lead isotopic data from Mesoproterozoic rocks in the Eagle Lake quadrangle, Essex County, New York

This data release includes whole rock (WR) geochemical data, and uranium-lead isotopic data collected using a sensitive high resolution ion microprobe-reverse geometry (SHRIMP-RG) instrument; the SHRIMP-RG is a type of secondary ion mass spectrometer (SIMS). Whole rock geochemistry data were analyzed at Bureau Veritas Commodities Canada Ltd. Laboratories in Vancouver, British Columbia, Canada. SHR
By
Florence Bascom Geoscience Center

Electron microprobe and 40Ar/39Ar isotopic data from west-central New Hampshire

This dataset accompanies planned publication 'Unmixing multiple metamorphic muscovite age populations with powder X-ray diffraction and 40Ar/39Ar analysis'. The 40Ar/39Ar and electron microprobe data are from samples adjacent to a lower greenschist facies shear zone in western New Hampshire. The geochronology coupled with the electron microprobe data provide a petrochronologic framework for the ro
By
Florence Bascom Geoscience Center

Data release for depth to bedrock from Connecticut Water Resources Bulletins

This data release consists of information from published tables in Connecticut Water Resources Bulletins (WRBs) transcribed into tabular digital format. Information about wells and test holes in the WRBs used in this data release consists of geographic location, depth to consolidated rock (bedrock depth), and depth of the well or test hole. The WRBs, published between 1966 and 1980 by the U.S. Geo
By
Florence Bascom Geoscience Center

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 heavy mineral concentrate that records the most ge
By
Florence Bascom Geoscience Center, Bascom ARgon Dating (BARD) Laboratory

Electron microprobe analyses of feldspars and petrographic, geochemical, and geochronologic data from the Hawkeye Granite Gneiss and Lyon Mountain Granite Gneiss in the Adirondacks of New York (ver. 2.0, May 2023)

Iron oxide-apatite (IOA) deposits of the Adirondack Mountains of New York locally contain elevated rare earth element (REE) concentrations (e.g. Taylor and others, 2019). Critical to evaluating resource potential is understanding the genesis of the IOA deposits that host the REE-rich minerals. As part of this effort, the U.S. Geological Survey (USGS) is conducting bedrock geologic mapping, geoch
By
Florence Bascom Geoscience Center, Bascom ARgon Dating (BARD) Laboratory

Petrophysical data collected on outcrops and rock samples from the eastern Adirondack Highlands, New York

Petrophysical data were collected in the eastern Adirondack Highlands during several field campaigns in 2016-2017. This data release provides magnetic susceptibility, gamma spectrometry, and density measurements on rock outcrops, hand samples, and during walking surveys. Rock types for the outcrops and samples were identified using standard field methods. Locations of the outcrops or samples were
By
Geology, Geophysics, and Geochemistry Science Center

GIS and Data Tables for Focus Areas for Potential Domestic Nonfuel Sources of Rare Earth Elements

In response to Executive Order 13817 of December 20, 2017, the U.S. Geological Survey (USGS) coordinated with the Bureau of Land Management (BLM) to identify 35 nonfuel minerals or mineral materials considered critical to the economic and national security of the United States (U.S.). Acquiring information on possible domestic sources of these critical minerals is the basis of the USGS Earth Mappi
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Earth Mapping Resources Initiative (Earth MRI)

Geochemistry of ore, host rock, and mine waste pile samples of iron oxide-apatite (IOA) deposits of the eastern Adirondack Highlands, New York, in relation to potential rare earth elements resources, 2016-2018

Thirty-four ore, twenty-nine mine waste, seven host rock, two pegmatite, and one slag sample were collected from iron oxide-apatite (IOA) mines in the eastern Adirondack Highlands near Mineville and Ticonderoga, New York, from March 2016 to August 2018. The waste pile samples included twenty-five samples collected from rubble-sized mine waste piles and four samples from processed tailings piles.
By
Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center
Filter Total Items: 14

Bedrock geologic map of the Woodstock quadrangle, Grafton County, New Hampshire

The bedrock geology of the Woodstock 7.5-minute quadrangle consists of highly deformed metasedimentary rocks of the Central Maine trough, including the Silurian Rangeley and Perry Mountain Formations and the Devonian Littleton Formation. The central, northern, and eastern parts of the quadrangle are underlain by the oldest rocks in the area, the Rangeley Formation. In the southwest and south-centr
By
Florence Bascom Geoscience Center

Percent-slope map showing historical anthracite coal-mining infrastructure at the northern end of the Lackawanna syncline, Wayne, Susquehanna, and Lackawanna Counties, Pennsylvania

Introduction Abandoned railroads and infrastructure from the anthracite coal-mining industry are significant features in abandoned mine lands and are an important part of history; however, these features are often lost and masked by the passage of time and the regrowth of forests. The application of modern light detection and ranging (lidar) topographic analysis, combined with field verification,
By
Florence Bascom Geoscience Center

Bedrock geologic map of the Crown Point quadrangle, Essex County, New York, and Addison County, Vermont

The bedrock geology of the 7.5-minute Crown Point quadrangle consists of deformed and metamorphosed Mesoproterozoic gneisses of the Adirondack Highlands unconformably overlain by weakly deformed lower Paleozoic sedimentary rocks of the Champlain Valley. The Mesoproterozoic rocks occur on the eastern edge of the Adirondack Highlands and represent an extension of the Grenville Province of Laurentia.
By
Florence Bascom Geoscience Center

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 Mounta
By
Florence Bascom Geoscience Center

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 the northeastern flank of the Chester dome. The alloc
By
Florence Bascom Geoscience Center

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 occupy the western part of the broader BHA. In the
By
Florence Bascom Geoscience Center

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 Ganderian margin arc-related rocks (Nashoba zone)
By
Florence Bascom Geoscience Center

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 quadrangle. The oldest metasedimentary rocks include th
By
Florence Bascom Geoscience Center

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 including pegmatite and the Chelmsford Granite, and
By
Florence Bascom Geoscience Center

Bedrock geologic map of Vermont

The Bedrock Geologic Map of Vermont is the result of a cooperative agreement between the U.S. Geological Survey (USGS) and the State of Vermont. The State's complex geology spans 1.4 billion years of Earth's history. The new map comes 50 years after the most recent map of the State by Charles G. Doll and others in 1961 and a full 150 years since the publication of the first geologic map of Vermont

Bedrock geologic map of the Grafton quadrangle, Worcester County, Massachusetts

The bedrock geology of the 7.5-minute Grafton, Massachusetts, quadrangle consists of deformed Neoproterozoic to early Paleozoic crystalline metamorphic and intrusive igneous rocks. Neoproterozoic intrusive, metasedimentary, and metavolcanic rocks crop out in the Avalon zone, and Cambrian to Silurian intrusive, metasedimentary, and metavolcanic rocks crop out in the Nashoba zone. Rocks of the Avalo

Bedrock geologic map of the Montpelier and Barre West quadrangles, Washington and Orange Counties, Vermont

The bedrock geology of the Montpelier and Barre West quadrangles consists of Silurian and Devonian metasedimentary rocks of the Connecticut Valley-Gaspe synclinorium (CVGS) and metasedimentary, metavolcanic, and metaintrusive rocks of the Cambrian and Ordovician Moretown and Cram Hill Formations. Devonian granite dikes occur throughout the two quadrangles but are more abundant in the Silurian and
Hydrologic technician showing a high-water mark on a debris line next to the Black River in Ludlow VT
Hydrologic technician showing a high-water mark on a debris line
Hydrologic technician showing a high-water mark on a debris line
Hydrologic technician showing a high-water mark on a debris line next to the Black River in Ludlow VT

Hydrologic technician showing a high-water mark on a debris line

Hydrologic technician showing a high-water mark on a debris line

Hydrologic technician showing a high-water mark on a debris line next to the Black River in Ludlow Vermont.

By
New England Water Science Center, New England Water Science Center
Hydrologic technician showing a high-water mark on a debris line next to the Black River in Ludlow VT

Hydrologic technician showing a high-water mark on a debris line

Hydrologic technician showing a high-water mark on a debris line

Hydrologic technician showing a high-water mark on a debris line next to the Black River in Ludlow Vermont.

By
New England Water Science Center, New England Water Science Center
Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River
Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River
Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River
Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

 Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

By
New England Water Science Center, New England Water Science Center
Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

 Langdon Street Bridge stream gage 04285800 on the North Branch Winooski River

By
New England Water Science Center, New England Water Science Center
High-water mark on door at Montpelier Federal Building
High-water mark on door at Montpelier, Vermont Federal Building
High-water mark on door at Montpelier, Vermont Federal Building
High-water mark on door at Montpelier Federal Building

High-water mark on door at Montpelier, Vermont Federal Building

High-water mark on door at Montpelier, Vermont Federal Building

High-water mark on door at Montpelier, Vermont Federal Building during major flood event in July 2023.

By
New England Water Science Center
High-water mark on door at Montpelier Federal Building

High-water mark on door at Montpelier, Vermont Federal Building

High-water mark on door at Montpelier, Vermont Federal Building

High-water mark on door at Montpelier, Vermont Federal Building during major flood event in July 2023.

By
New England Water Science Center
High-water mark on door at Federal Building, Montpelier, Vermont
High-water mark on door at Federal Building, Montpelier, Vermont
High-water mark on door at Federal Building, Montpelier, Vermont
High-water mark on door at Federal Building, Montpelier, Vermont

High-water mark on door at Federal Building, Montpelier, Vermont

High-water mark on door at Federal Building, Montpelier, Vermont

High-water mark on door at Federal Building, Montpelier, Vermont during major flood event in July 2023.

By
New England Water Science Center
High-water mark on door at Federal Building, Montpelier, Vermont

High-water mark on door at Federal Building, Montpelier, Vermont

High-water mark on door at Federal Building, Montpelier, Vermont

High-water mark on door at Federal Building, Montpelier, Vermont during major flood event in July 2023.

By
New England Water Science Center
Flooded stairwell to Montpelier, Vermont Federal Building
Flooded stairwell to Montpelier, Vermont Federal Building
Flooded stairwell to Montpelier, Vermont Federal Building
Flooded stairwell to Montpelier, Vermont Federal Building

Flooded stairwell to Montpelier, Vermont Federal Building

Flooded stairwell to Montpelier, Vermont Federal Building

Flooded stairwell to Montpelier, Vermont Federal Building during historical flood event.

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New England Water Science Center, New England Water Science Center
Flooded stairwell to Montpelier, Vermont Federal Building

Flooded stairwell to Montpelier, Vermont Federal Building

Flooded stairwell to Montpelier, Vermont Federal Building

Flooded stairwell to Montpelier, Vermont Federal Building during historical flood event.

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New England Water Science Center, New England Water Science Center
A boat sits along a dock on Paradox Lake. The autumn colored trees are reflected in the placid lake.
Autumn colors reflected on Paradox Lake in the Adirondack Mountains
Autumn colors reflected on Paradox Lake in the Adirondack Mountains
A boat sits along a dock on Paradox Lake. The autumn colored trees are reflected in the placid lake.

Autumn colors reflected on Paradox Lake in the Adirondack Mountains

Autumn colors reflected on Paradox Lake in the Adirondack Mountains

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.

By
Florence Bascom Geoscience Center
A boat sits along a dock on Paradox Lake. The autumn colored trees are reflected in the placid lake.

Autumn colors reflected on Paradox Lake in the Adirondack Mountains

Autumn colors reflected on Paradox Lake in the Adirondack Mountains

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.

By
Florence Bascom Geoscience Center
Filter Total Items: 77

Implementation plan of the National Cooperative Geologic Mapping Program strategy—Northeast region of the United States: New York and New England

Complexly deformed igneous, metamorphic, and sedimentary rocks form the bedrock of the Northeast region of the United States. Variably thick unconsolidated sediments deposited by glacial, fluvial, and eolian systems locally cover the bedrock. New geologic mapping focuses on areas lacking modern, detailed studies or syntheses, and contributes to existing framework research. This report addresses pl
Authors
Gregory J. Walsh, Margaret A. Thomas, Robert G. Marvinney, Stephen B. Mabee, Frederick H. Chormann, Andrew Kozlowski, Marjorie H. Gale, Jon Kim, Brian Savage
By
Florence Bascom Geoscience Center

An apparent dip calculator for spreadsheets

This report and spreadsheet calculator contain Microsoft Excel-based equations that are useful in structural geology to calculate plunge or apparent dip when measuring lineations on a plane. The spreadsheet allows users to measure the trend or the plunge of a lineation and calculate the corresponding unknown value of trend or plunge. The spreadsheet provides the user with two options:Option 1: Cal
Authors
Gregory J. Walsh
By
Florence Bascom Geoscience Center

Age and tectonic setting of the Quinebaug-Marlboro belt and implications for the history of Ganderian crustal fragments in southeastern New England, USA

Crustal fragments underlain by high-grade rocks represent a challenge to plate reconstructions, and integrated mapping, geochronology, and geochemistry enable the unravelling of the temporal and spatial history of exotic crustal blocks. The Quinebaug-Marlboro belt (QMB) is an enigmatic fragment on the trailing edge of the peri-Gondwanan Ganderian margin of southeastern New England. SHRIMP U-Pb geo
Authors
Gregory J. Walsh, John N. Aleinikoff, Robert A. Ayuso, Robert P. Wintsch
By
Geology, Energy & Minerals Science Center, Geology, Geophysics, and Geochemistry Science Center, Florence Bascom Geoscience Center

New interpretations of the ages and origins of the Hawkeye Granite Gneiss and Lyon Mountain Granite Gneiss, Adirondack Mountains, NY: Implications for the nature and timing of Mesoproterozoic plutonism, metamorphism, and deformation

The Hawkeye Granite Gneiss and Lyon Mountain Granite Gneiss are widespread Mesoproterozoic plutonic rocks that occur in the amphibolite- to granulite-facies Adirondack Highlands of northern New York, USA. The strongly deformed Hawkeye Granite Gneiss, previously dated by zircon multi-grain thermal ionization mass spectrometry (TIMS) U-Pb analyses at about 1100 Ma, was intruded by the weakly deforme
Authors
John N. Aleinikoff, Gregory J. Walsh, Ryan J. McAleer
By
Mineral Resources Program, Florence Bascom Geoscience Center, Geology, Geophysics, and Geochemistry Science Center

Renewing the National Cooperative Geologic Mapping Program as the Nation’s authoritative source for modern geologic knowledge

This document presents the renewed vision, mission, and goals for the National Cooperative Geologic Mapping Program (NCGMP). The NCGMP, as authorized by the National Cooperative Geologic Mapping Act of 1992 (Public Law 102-285, 106 Stat. 166 and its reauthorizations), is tasked with expediting the production of a geologic database for the Nation based on modern geologic maps and their supporting d
Authors
John Brock, Karen Berry, James Faulds, Richard Berg, Kyle House, Michael Marketti, Darcy McPhee, Kevin M. Schmidt, James Schmitt, David R. Soller, David Spears, Ren A. Thompson, Harvey Thorleifson, Gregory J. Walsh
By
National Cooperative Geologic Mapping Program, Geosciences and Environmental Change Science Center

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 muscovite
Authors
Ryan J. McAleer, David Bish, Michael J. Kunk, Peter M. Valley, Gregory J. Walsh, Robert Wintsch
By
National Cooperative Geologic Mapping Program, Florence Bascom Geoscience Center

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. Aeromagnetic total field data reflect highly magnetic leu
Authors
Anjana K. Shah, Ryan D. Taylor, Gregory J. Walsh, Jeffrey Phillips
By
Geology, Geophysics, and Geochemistry Science Center

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 heavy mineral concentrate that records the most ge

Authors
Ryan J. McAleer, Aaron M. Jubb, Paul C. Hackley, Gregory J. Walsh, Arthur J. Merschat, Sean P. Regan, William C. Burton, Jorge A. Vazquez
By
Energy Resources Program, Volcano Hazards Program, Florence Bascom Geoscience Center, Volcano Science Center, Bascom ARgon Dating (BARD) Laboratory

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 locations throughout the valley including the Saint-
Authors
Gregory J. Walsh, Brooks P. Proctor, Karri R. Sicard, Peter M. Valley
By
Florence Bascom Geoscience Center

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

Authors
Peter M. Valley, Gregory J. Walsh, Arthur J. Merschat, Ryan J. McAleer
By
Florence Bascom Geoscience Center, Bascom ARgon Dating (BARD) Laboratory

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 paragneiss, gabbro, anorthosite, or potassically al
Authors
Ryan Taylor, Anjana K. Shah, Gregory J. Walsh, Cliff D. Taylor
By
Geology, Geophysics, and Geochemistry Science Center, Florence Bascom Geoscience Center

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 decipher the structural evolution of these regions. Th
Authors
Sean Regan, Gregory J. Walsh, Michael L. Williams, Jeffrey R. Chiarenzelli, Megan E. Toft, Ryan J. McAleer
By
Florence Bascom Geoscience Center, Bascom ARgon Dating (BARD) Laboratory, Reston Electron Microbeam Laboratory

*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

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