U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY Bedrock Geologic Map of the Nashua South Quadrangle, Hillsborough County, New Hampshire, and Middlesex County, Massachusetts [Scale 1:24,000] by Gregory J. Walsh (1) Richard H. Jahns (2) and John N. Aleinikoff (3) Scientific Investigations Map 3200 2013 version 1.0 Prepared in cooperation with the COMMONWEALTH OF MASSACHUSETTS, Massachusetts Geological Survey and the STATE OF NEW HAMPSHIRE, New Hampshire Geological Survey ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Date of latest revision: December 19, 2012 ________________________________ (1) U.S. Geological Survey Montpelier, Vermont 05601 (2) Stanford University and U.S. Geological Survey, deceased (3) U.S. Geological Survey Denver, Colorado 80225 This report consists of a map, text pamphlet, and GIS database. All parts are available only at: http://pubs.usgs.gov/sim/3200/. Suggested citation: Walsh, G.J., Jahns, R.H., and Aleinikoff, J.N., 2013, Bedrock geologic map of the Nashua South quadrangle, Hillsborough County, New Hampshire, and Middlesex County, Massachusetts: U.S. Geological Survey Scientific Investigations Map 3200, 1 sheet, scale 1:24,000, 31-p. pamphlet. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Source of Geologic Data: Original data. Geology mapped by Walsh in 2006, by Jahns in 1939-40 (MA) and 1951 (NH). Geochronology by Aleinikoff, 2007-08. A preliminary version of the geology of the Nashua South quadrangle was published by Jahns and others (1959). This report supersedes the Nashua South part of the 1959 report. Jahns, R.H., Willard, M.E., and White, W.S., 1959, Preliminary bedrock geologic map of the Lowell-Westford area, Massachusetts: U.S. Geological Survey Open-File Report 59-70, scale 1:31,680, 1 map. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File directory layout: | README.TXT---ASCII text description (this file) | METADATA.HTML---Metadata file in HTML format | |---BASE---Folder contains basemap image files and worldfiles | (base.zip) | |---EXPORT---Folder contains Arc/Info GIS export-interchange files (e00) | Does not contain PHOTO database, see shapefile instead | (export.zip) | |---GoogleEarth---Folder contains 3 KMZ files showing: | - arcs and polygons from GIS data | - raster image of provisional cartographic map | - 3D model with two cross-sections and map | | |---PHOTOS---Folder contains 158 photographs of the geology and landscape | Includes an Excel spreadsheet | (photos.zip) | |---SHAPE---Folder contains ArcGIS shapefiles & lookup table for CONTX | polygon coverage | (shape.zip) | |---SYMBOLS---ArcPlot symbols used for plotting structure data | (symbols.zip) | | |--SIM_3200_map_sheet.pdf---Geologic map |---WEB--------| | |--SIM3200_pamphlet.pdf---Text pamphlet | | | |--NashuaS.GIF---Browse graphic of map | | | |--NashuaS.JPG---Image graphic of map (200 dpi) | (Adobe Portable Document Format = pdf) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ A subset of the contents of this readme.txt file are also included in the metadata for this report. This readme.txt, however, contains greater detail than the metadata. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Description: The bedrock geology of the 7.5-minute Nashua South, NH-MA quadrangle consists of deformed Silurian to Jurassic crystalline metamorphic and intrusive igneous rocks. The geology was mapped during 2006 and 1939-1951 at a scale of 1:24,000. The bedrock geology was mapped using standard techniques. Location information during modern mapping was collected with a GPS receiver (GPS model: Garmin eTrex Venture). Locational data for historic data (1939-1951) was digitized by Walsh from scanned unpublished map sheets compiled by Richard Jahns. The 7.5-minute Nashua South quadrangle was formerly named the Tyngsborough quadrangle. Jahns mapped the New Hampshire part of the Tyngsborough quadrangle in 1951, and the Massachusetts part from 1939-1941. Scanned copies of Jahns’ unpublished manuscript maps were obtained from the Richard Jahns Collection at the Branner Earth Sciences Library, Stanford University, Palo Alto, California. The line and polygon data were compiled in Adobe Illustrator over the topographic basemap. Field and compilation sheets were scanned and registered in Illustrator. Topographic basemap separates were scanned at 400 dpi. Line and polygon data were exported from Illustrator in DXF format to Arc/Info version 9.3. Point data by Walsh were collected with GPS and a hand-held 3COM Palm Pilot III PDA computer. Data from the PDA were imported to ArcGIS version 9.3 as ASCII text files and joined with GPS point data to create shapefiles. Jahns' strike and dip data were heads-up digitized in Arc/Info. The GPS data were collected in Latitude and Longitude in degrees minutes and seconds in WGS84 datum. GPS data were projected to the Massachusetts Stateplane coordinate system (FIPS zone 2001) in NAD83 datum, with units in meters. GPS locations were compared to the topographic basemap of the area and repositioned to match the base. The original coordinates remain in the STRUCTURE database. After editing in Arc/Info, all arcs, polygons, and points were converted to shapefiles. Data in the Massachusetts State Plane coordinate system were re-projected to the New Hampshire State Plane coordinate system. Line and polygon data were edited in Arc/Info and converted to shapefiles. Shapefiles were plotted in ArcMap and exported to Illustrator. Final cartography was done in Adobe Illustrator. Direct questions or comments on this report to: Gregory J. Walsh U.S. Geological Survey P.O. Box 628 Montpelier, Vermont 05601 Tel: 802-828-4528 e-mail: gwalsh@usgs.gov ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The GIS point, line, and polygon data associated with this report are provided in two common GIS formats: shapefile (shp) and interchange (e00). The GIS data were created in ArcGIS and ARC/INFO version 9.3 on an Dell PC running a Windows OS. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Note on Metadata: FGDC compliant metadata for the report is available in HTML format. The metadata file was created in ArcGIS 9.3. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Projection Information: Massachusetts Stateplane coordinate system (Zone 4151, FIPS zone 2001) in NAD83 datum units in meters (file prefix "ns" is an abbreviation of "Nashua South") AND New Hampshire Stateplane coordinate system (Zone 4676, FIPS zone 2008) in NAD83 datum units in feet (files with prefix "211") ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Computer Files: Some files have been archived using WinZip. Useful URL: http://winzip.com ******************************************************************** The following is a brief description of the geologic data layers, tables, and non-standard attributes used in this report. ******************************************************************** CONTX - Polygon data layer of bedrock geologic map units ns_contx (MA) 211_contx (NH) CONTX is divided into shapefiles for arcs, polygons, labels, and tic marks. Polygons - CONTX.PAT items: CODE - Bedrock geologic map unit code LITH_UNIT - same as CODE Valid entries of CODE (see Lookup table for other attributes) CODE FORMATION Jd diabase dikes Dp pegmatite Dcfgr Chelmsford Granite Dcgr Chelmsford Granite SbDc migmatitic Berwick Formation Dadg Ayer Granodiorite Dadp Ayer Granodiorite Dad Ayer Granodiorite DSdi diorite-gabbro suite DSgn diorite-gabbro suite Sb Berwick Formation Lookup table - CONTX_LI.CSV CONTX_LI.XLS Bedrock lithology attribute lookup table in comma-delimited text and Microsoft Excel formats. If you are using Arc/Info you can access the data in this table using either the JOINITEM or RELATE functions and the item LITH_UNIT. You will first need to convert the file to a DBF file. CONTX is the Arc/INfo coverage, and includes arcs, polygons, labels, and tic marks. Alternatively, you can use the polygon shapefile where the lookup table CONTX_LI.TXT has already been joined (ns_contx_polygon.shp) CONTX_LI.TXT items: CODE = map unit designator (same as LITH_UNIT) AGE_SORT = order to sort by age (1 = youngest) LITH_UNIT = map unit designator SURF_BED = surficial or bedrock unit LITHSIMP = simplified description of lithology (rock type) LITHPRI = primary lithology in the map unit LITHSEC = secondary lithology in the map unit ZONE = Merrimack belt (or terrane) GROUP = group name FORMATION = formation name MEMBER = member name ROCKCLASS = generalized rock classification AGE = geologic age of the map unit CHRON_AGE = geochronologic age in this report in millions of years (Ma) CHRON_METH = method for determining geochronologic age COLOR = prinicipal colors of rock MINPRI = principal or most characteristic minerals Arcs - Line data layer of geologic contacts and faults CONTX.AAT or arc shapefile Items: TYPE - fault or contact LINETYPE - type of faults, entries used in this database: 'fault?' = a conjectural fault 'strikeslip' = a strike-slip fault Tic marks: 4 corner tic marks from Mass GIS: MassGIS is the Commonwealth's Office of Geographic and Environmental Information http://www.mass.gov/mgis/massgis.htm 2016 2017 + + + + 1916 1917 Corner tic marks from the statewide coverage of USGS 7.5-minute quadrangles. NOTE: The states of Massachusetts and New Hampshire use different coordinate systems and projections for their statewide GIS data. The data in this report are available in both projections (see above) but the four corner TIC marks are labelled according to the Massachusetts numbering system. _________________________________________________________________ EXPOSURE - Unattributed polygon data layer of bedrock outcrops examined during mapping ns_exposure (MA) 211_exposure (NH) _________________________________________________________________ STRUCTURE - Point data layer of ductile and brittle structural geology ns_structure (MA) 211_structure (NH) STRUCTURE.PAT items: STATION - Number of field station for Walsh's data Station values of 0 are Jahns' and were heads-up digitized TYPE - Refers to the general type of geologic feature. Valid entries include 'planar', 'linear', or 'other' SUB_TYPE - Refers to the specific geologic structure STRIKE - Angle measured from North in right-hand rule, units in degrees. DIP - Dip value (planar data) or plunge value (linear data), units in degrees DIPDIR - Direction of dip (planar data) or trend (linear data), units in degrees FRACTURE - 'Y' indicates feature is a fracture PARTING - 'Y' indicates the planar feature exhibits parting or fracturing parallel to the surface measured SYMBOL - Arc/Info symbol number THROUGHOI - 'Y' indicates the measured brittle feature is throughgoing and passes through the entire outcrop. REL_AGE - Refers to the relative age of ductile fabrics. Valid entries include: n = Relative age is the dominant fabric, S2 n+1 = maybe S2 or S3 n+2 = probably S3 FAULTMOVE - movement sense of brittle fault Valid entries include: normal, reverse, left lateral, right lateral, thrust NO_MSMTS - Number of features with same orientation. Valid for SUB_TYPE = 'joint' and 'joint set'. TERMINATIO - Termination of joints where known valid entries include: 'blind', 'abutting', 'crossing' TOPOFEAT - Topographic feature parallel to a geologic structure. Valid entries include: 'cliff' LITHOLOGY - Freeform text indicating the rock type in which the feature was measured. Used for rock type of dikes and sills, and locations where multiple rock types occur at one station SYMBOL - Refers to the symbol number from the GEOLOGY1.MRK markerset; used for plotting in Arcplot. SYMBOL_ANG - Refers to a standard Cartesian angle measured from East; used for symbol rotation and plotting in Arcplot, units in degrees Note -- The following three diagrams show an explanation of the geometry of STRIKE, DIPDIR, and SYMBOL_ANG: For STRIKE and DIPDIR: 0 North = 0 | East = 90 270 -----|----- 90 South = 180 | West = 270 180 For SYMBOL_ANG: 90 North = 90 | East = 0 180 -----|----- 0 South = 270 | West = 180 270 SYMBOL_ANG is used for symbol rotation. In ARC/INFO calculate pseudo item $angle = symbol_ang Planar symbols with symbol_ang = 0 look like this: __________ \/ Linear symbols with symbol_ang = 0 look like this: -----> ROTATION - Rotation sense of minor folds as viewed down plunge. Valid entries: 'cc' = counterclockwise and 'cw' = clockwise. SPACING - Spacing of joints in joint sets, units in meters WIDTH - Width or thickness of dike or vein, units in meters MIN1 - Primary mineral MIN2 - Secondary mineral MIN3 - Tertiary mineral Note on MIN1, MIN2, and MIN3 -- The aforementioned 3 items are used to describe minerals in veins or mineral lineations. Valid entries, some from from Kretz (1983), are used in the report: zeo = zeolites qtz = quartz amp = amphibole hbl = hornblende ms = muscovite grt = garnet Kretz, R., 1983, Symbols for rock-forming minerals: American Mineralogist, v. 68, nos. 1-2, p. 277-279. SAMPLE_TYP - Freeform text indicating U-Pb zircon sample location for geochronology in this report Raw GPS coordinates collected by Walsh (WGS84 datum) LAT - LATitude in decimal degrees LONG - LONGitude in decimal degrees ____________________________________________________________ PHOTO - Point data layer of photographs by Walsh; includes landscape and outcrop photos in a shapefile (ns_photo) Items: STATION - Number of field station TYPE - Valid entries include 'other' SUB_TYPE - Refers to the specific geologic feature, in this case 'photo'. PHOTO_FILE - Filename of JPG format color photograph Used for hyperlinks (Layer Properties, Display, Support Hyperlinks...) NOTES - Description of the photo FIGURE - Indicates the figure number of photos used in the text pamphlet The PHOTO shapefile is desgined for use with the ArcMap hyperlink tool. There are 158 digital photos located in the PHOTOS directory. Users can copy the photos to the same directory as the shapefile, or copy the photos to their own folder and then specify the path: In ArcMap - File, Map Document Properties, Hyperlink Base A Microsoft Excel file (NS_photos.xls) also lists the items in this database. ************************************************************************ The following is a description of the base maps used in this report: The base maps consist of: Four files as TIFF format bitmaps and worldfiles HYPSO - Hypsography - brown separate HYDRO - Surface water - blue separate CULTURE - Primary culture originally on black and red separates includes roads, buildings, etc. CULTURE2 - Secondary culture from 1979 photorevisions from purple separate TIFF format maps: Scanned black and white bitmap images in uncompressed TIFF format. Scanned at 400 dpi from film positives of the USGS 7.5-minute Nashua South, NH-MA topographic map (1965, photorevised 1979). Images registered to the 4 corner tics in ArcGIS. Supplementary base files are also provided as follows: nashuasouthr - TIFF image of the combined topo base. Obtained from the Office of the Massachusetts State Geologist http://www.geo.umass.edu/stategeologist/frame_maps.htm Projection: Massachusetts State Plane Meters, North American Datum 1983 (NAD83), FIPS zone 2100 (Zone 4151). drg211 - Digital Raster Graphic (DRG) TIFF image of the combined topo base. Obtained from NH GRANIT - New Hampshire's Statewide GIS Clearinghouse http://www.granit.unh.edu/ Projection: New Hampshire State Plane Feet, North American Datum 1983 (NAD83), FIPS zone 2800 (Zone 4676). ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ END