README for U.S. Geological Survey Scientific Investigations Map 3440 TITLE: Bedrock Geologic Map of the Mount Ascutney 7.5- x 15-Minute Quadrangle, Windsor County, Vermont, and Sullivan County, New Hampshire By: Gregory J. Walsh, Peter M. Valley, Peter J. Thompson, Nicholas M. Ratcliffe, Brooks P. Proctor, and Karri R. Sicard PREPARED IN COOPERATION WITH: State of Vermont, Vermont Agency of Natural Resources, Vermont Geological Survey; State of New Hampshire, Department of Environmental Services, New Hampshire Geological Survey; and the National Park Service ABSTRACT: 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 allochthonous Cambrian through Ordovician rocks include the Moretown and Cram Hill Formations and the North River Igneous Suite; these rocks structurally overlie the Chester dome along the Keyes Mountain thrust fault. Silurian and Devonian metasedimentary and metavolcanic rocks of the Connecticut Valley trough (CVT) unconformably overlie the pre-Silurian rocks. The easternmost extent of the CVT in New Hampshire is exposed in the Meriden antiform. Ordovician to Silurian and Devonian metasedimentary rocks of the Bronson Hill anticlinorium structurally overlie the CVT along the Monroe thrust fault. The oldest part of the Bronson Hill anticlinorium, called the Bronson Hill arc, consists of Ordovician metamorphosed volcanic, plutonic, and sedimentary rocks of the Ammonoosuc Volcanics, the Partridge Formation, and the Oliverian Plutonic Suite. The rocks of the Bronson Hill arc may be partly correlative with the pre-Silurian rocks above the Chester dome and are exposed in two fault-bounded structural belts (Cornish City and Claremont belts) and in the Sugar River dome. Collectively, these belts form the regional Orfordville anticlinorium, Hardscrabble synclinorium, and the western part of the broader Bronson Hill anticlinorium in western New Hampshire. Silurian to Devonian metasedimentary rocks of the Clough Quartzite, and Fitch and Littleton Formations unconformably overlie the rocks of the Bronson Hill arc. Devonian granitic and pegmatitic dikes and sills of the New Hampshire Plutonic Suite intruded previously deformed rocks. Post-tectonic Cretaceous plutonic and volcanic rocks of the Ascutney Mountain Intrusive Complex underlie Mount Ascutney. Because of the historically significant scientific research, and its prominence in the landscape, Mount Ascutney is commonly regarded as Vermont's most famous volcano. The bedrock geology was mapped to study the tectonic history of the area and to provide a framework for ongoing characterization of the bedrock of Vermont and New Hampshire. This Scientific Investigations Map of the Mount Ascutney 7.5- x 15-minute quadrangle consists of sheets 1 and 2 as well as a geographic information system (GIS) database that includes bedrock geologic units, faults, outcrops, structural geologic information, geochemistry, and photographs. Sheet 1 of the report includes a bedrock geologic map, a correlation of map units, and a description of map units. Sheet 2 includes a discussion of the geology, references, three cross sections from the geologic map on sheet 1, igneous rock geochemistry results of the main map units from the Mount Ascutney stock, a tectonic map showing major structural features, and a structural domain map showing the orientation and distribution of brittle features. PURPOSE: The bedrock geologic map of the Mount Ascutney 7.5- x 15-minute quadrangle is intended to serve as a foundation for applying geologic information to problems involving land use decisions, groundwater availability and quality, earth resources such as natural aggregate for construction, assessment of natural hazards (earthquakes), and engineering and environmental studies for waste disposal sites and construction projects. SUPPLEMENTARY INFORMATION: This digital database was compiled in compliance with the USGS National Cooperative Geologic Mapping Program ("GeMS") geologic map database schema (https://ngmdb.usgs.gov/Info/standards/GeMS/) using ArcGIS version 10.7. This release is a file geodatabase that contains geologic map feature classes and stand-alone tables. ArcGIS-compatible GIS software is required to use the files of this database. The geodatabase is delivered in a single zipped folder in this release for ease of transfer. The scale of the source maps limits the usable spatial resolution of the database to 1:24,000 scale or greater. Feature classes are symbolized according to the FGDC Digital Cartographic Standard for Geologic Map Symbolization using ArcGIS Representation Classes where available. For more information about geologic map symbology, see the FGDC Digital Cartographic Standard for Geologic Map Symbolization web page (https://ngmdb.usgs.gov/fgdc_gds/geolsymstd.php). PROJECTION AND DATUM: All data is in North American Datum 1983, New Hampshire State Plane coordinate system (FIPS zone 2800), units in feet MAP DOCUMENT: Contains layer files for this map. This map document was created in ArcGIS 10.7. This file is zipped with the geodatabase (sim3440_MountAscutney_database.zip) MountAscutneyNHVTSIM3440.mxd GEODATABASE: The "GeMS" compliant database contents are described below. MountAscutneyNHVTSIM3440.gdb.................................(Geodatabase) ================================================================================= GeologicMap.............................................(Feature dataset) ========================================================================= CartographicLines..................................(Polyline feature class with FGDC compliant metadata) ContactsAndFaults..................................(Polyline feature class with FGDC compliant metadata) DataSourcePolys....................................(Polygon feature class with FGDC compliant metadata) GenericPoints......................................(Point feature class with FGDC compliant metadata) GeoChemPoints......................................(Point feature class with FGDC compliant metadata) GeochronPoints.....................................(Point feature class with FGDC compliant metadata) GeologicLines......................................(Polyline feature class with FGDC compliant metadata) MapUnitOverlayPolys................................(Polygon feature class with FGDC compliant metadata) MapUnitPolys.......................................(Polygon feature class with FGDC compliant metadata) OrientationPoints..................................(Point feature class with FGDC compliant metadata) OtherPolys.........................................(Polygon feature class with FGDC compliant metadata) PhotoPoints........................................(Point feature class with FGDC compliant metadata) Stations...........................................(Point feature class with FGDC compliant metadata) ========================================================================== DataSources.............................................(Non-spatial table with FGDC compliant metadata) DescriptionOfMapUnits...................................(Non-spatial table with FGDC compliant metadata) GeoMaterialDict.........................................(Non-spatial table with FGDC compliant metadata) Glossary................................................(Non-spatial table with FGDC compliant metadata) METADATA: Metadata files are valid for both the geodatabase feature classes and open-access shapefiles. Metadata is contained in a single zipped folder (sim3440_MountAscutney_metadata.zip) ================================================================================= GeologicMap.xml..............................................(Feature Dataset level FGDC compliant metadata) CartographicLines.xml........................................(Feature class level FGDC compliant metadata) ContactsAndFaults.xml........................................(Feature class level FGDC compliant metadata) DataSourcePolys.xml..........................................(Feature class level FGDC compliant metadata) GenericPoints.xml............................................(Feature class level FGDC compliant metadata) GeoChemPoints.xml............................................(Feature class level FGDC compliant metadata) GeochronPoints.xml...........................................(Feature class level FGDC compliant metadata) GeologicLines.xml............................................(Feature class level FGDC compliant metadata) MapUnitOverlayPolys.xml......................................(Feature class level FGDC compliant metadata) MapUnitPolys.xml.............................................(Feature class level FGDC compliant metadata) OrientationPoints.xml........................................(Feature class level FGDC compliant metadata) OtherPolys.xml...............................................(Feature class level FGDC compliant metadata) PhotoPoints.xml..............................................(Feature class level FGDC compliant metadata) Stations.xml.................................................(Feature class level FGDC compliant metadata) DataSources.xml..............................................(Non-spatial table FGDC compliant metadata) DescriptionOfMapUnits.xml....................................(Non-spatial table FGDC compliant metadata) Glossary.xml.................................................(Non-spatial table FGDC compliant metadata) GeoMaterialDict.xml..........................................(Non-spatial table FGDC compliant metadata) BASEMAP: These files are contained in a single zipped folder (sim3440_MountAscutney_basemap.zip). MountAscutneyNHVTSIM3440Culture.tif MountAscutneyNHVTSIM3440Neatline.shp MountAscutneyNHVTSIM3440Topography.tif MountAscutneyNHVTSIM3440Water.tif MountAscutneyNHVTSIM3440Water.shp PHOTOS: These files are contained in a single zipped folder (sim3440_MountAscutney_photos.zip). OPEN-ACCESS VERSIONS: To improve access to this product, an open-access version of these data are included with this release. Some field names may have been truncated when converting from geodatabase feature classes to shapefiles. A text file (logfile.txt) is available with information regarding changed field names and name changes to individual feature classes. These files are available as a single zipped folder (sim3440_MountAscutney_openaccess.zip) ================================================================================= ContactsAndFaults.shp..............................(Polyline feature class with FGDC compliant metadata) DataSourcePolys.shp................................(Polygon feature class with FGDC compliant metadata) GenericPoints.shp..................................(Point feature class with FGDC compliant metadata) GenericSamples.shp.................................(Point feature class with FGDC compliant metadata) GeochronPoints.shp.................................(Point feature class with FGDC compliant metadata) GeologicLines.shp..................................(Polyline feature class with FGDC compliant metadata) MapUnitOverlayPolys.shp............................(Polygon feature class with FGDC compliant metadata) MapUnitPolys.shp...................................(Polygon feature class with FGDC compliant metadata) OrientationPoints.shp..............................(Point feature class with FGDC compliant metadata) OtherPolys.shp.....................................(Polygon feature class with FGDC compliant metadata) PhotoPoints.shp....................................(Point feature class with FGDC compliant metadata) Stations.shp.......................................(Point feature class with FGDC compliant metadata) ================================================================================= DataSources.txt..............................................(Non-spatial table. Pipe delimited fields, pipe character = "|") DescriptionOfMapUnits.txt....................................(Non-spatial table. Pipe delimited fields, pipe character = "|") GeoMaterialDict.txt..........................................(Non-spatial table. Pipe delimited fields, pipe character = "|") Glossary.txt.................................................(Non-spatial table. Pipe delimited fields, pipe character = "|") ================================================================================= DataSources.csv..............................................(Non-spatial table) DescriptionOfMapUnits.csv....................................(Non-spatial table) GeoMaterialDict.csv..........................................(Non-spatial table) Glossary.csv.................................................(Non-spatial table)