| Postglacial deposits of the Heath-Northfield-Southwick-Hampden 24-quadrangle area in the Connecticut Valley region, west-central Massachusetts - postglacial | |
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Data format: Shapefile File or table name: postglacial Coordinate system: State Plane Coordinate System 1983 Theme keywords: surficial geology, stratified materials, stratified deposits, till, glacial deposits, stream terrace, alluvium, swamp deposits, artificial fill, dune, talus |
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Abstract:
The postglacial data layer is part of a comprehensive study to produce a statewide digital map of the surficial geology at 1:24,000 scale. This compilation of surficial geologic materials defines the boundaries between glacial till, glacial stratified deposits, and overlying postglacial deposits. The postglacial layer shows areas of swamp deposits, floodplain alluvium, and artificial fill for a twenty-four-quadrangle area in west-central Massachusetts. Swamp polygons may overlie alluvium polygons; artificial fill polygons may overlie areas of swamp or alluvium. This data layer should be used in conjunction with the underlying till, stratified_deposits, and early_postglacial data layers. |
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Metadata elements shown with blue text are defined in the Federal Geographic Data Committee's (FGDC) Content Standard for Digital Geospatial Metadata (CSDGM). Elements shown with green text are defined in the ESRI Profile of the CSDGM. Elements shown with a green asterisk (*) will be automatically updated by ArcCatalog. ArcCatalog adds hints indicating which FGDC elements are mandatory; these are shown with gray text.
The postglacial data layer is part of a comprehensive study to produce a statewide digital map of the surficial geology at 1:24,000 scale. This compilation of surficial geologic materials defines the boundaries between glacial till, glacial stratified deposits, and overlying postglacial deposits. The postglacial layer shows areas of swamp deposits, floodplain alluvium, and artificial fill for a twenty-four-quadrangle area in west-central Massachusetts. Swamp polygons may overlie alluvium polygons; artificial fill polygons may overlie areas of swamp or alluvium. This data layer should be used in conjunction with the underlying till, stratified_deposits, and early_postglacial data layers.
The purpose of this study is to provide fundamental geologic data for the evaluation of natural resources, hazards, and land information within the Commonwealth of Massachusetts. The postglacial deposits data layer is part of a comprehensive effort to produce a statewide digital map of the surficial geology at 1:24,000 scale. This compilation of surficial geologic materials defines the boundaries between glacial till, glacial stratified deposits, and overlying postglacial deposits. The postglacial layer shows areas of swamp deposits, floodplain alluvium, and artificial fill deposits for a twenty-four-quadrangle area in west-central Massachusetts. This data layer should be used in conjunction with the underlying till, stratified_deposits, and early-postglacial data layers. This map of twenty-four quadrangles revises previous digital surficial geologic maps (Stone and others, 1993; MassGIS, 1999) that were compiled on base maps at regional scales of 1:250,000.
publication date
No restrictions or legal prerequisites for using the data. The data are suitable for use at appropriate scale, and are not intended for maps printed at scales with higher resolution than 1:24,000 scale (1 inch = 2,000 feet). Although this data set has been used by the U.S. Geological Survey and the Commonwealth of Massachusetts, neither the U.S. Geological Survey nor the United States Government nor the Commonwealth of Massachusetts makes any warranty, expressed or implied, nor assumes any legal liability or responsibility for the accuracy of these data or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey, the United States Government, or the Commonwealth of Massachusetts in the use of these data or related materials. The user assumes the entire risk related to the use of these data. Once the data are distributed to the user, modifications made to the data by the user should be noted in the metadata. When printing these data on a map or using them in a software application, analysis, or report, please acknowledge the U.S. Geological Survey as the source for this information.
101 Pitkin St.
Multiple agencies and individuals contributed to this data layer: MassGIS scanned and georeferenced paper copies of the published surficial geologic maps for fifteen quadrangles; the Office of the Massachusetts State Geologist vectorized the georeferenced images and compiled geologic units in order to digitally retain the original information on the published maps (Mabee and others, 2004); U.S. Geological Survey personnel compiled and digitized the basic units for nine unpublished quadrangles from scanned field maps, and then joined and edge-matched the twenty four quadrangles in order to form a seamless geologic map.
Attributes have been visually checked by the compilers.
Polygon features conform to the following topological rules. There are no duplicate polygons. Polygons do not self overlap. Swamp deposits may overlap floodplain alluvium polygons. Artificial fill polygons may overlie swamp or alluvium polygons. No automated procedures or tests were performed to guarantee desired topology other than visual inspection.
The completeness of the data reflects the feature content of the basic units chosen for this interim product for all data sources. Additional information can be found on the data sources, which may be utilized in future compilations. The layer is complete in the sense that it accurately reflects the postglacial units for this twenty-four-quadrangle area, noting that edits (including additional units) may occur to this data set when it is edge-matched to surrounding quadrangles during future compilations.
The horizontal positional accuracy of these data complies with the United States National Map Accuracy Standards for 1:24,000-scale maps. According to this standard, not more than 10 percent of the locations tested are to be in error by more than 1/50 inch (40 feet) measured on the publication scale of a USGS 7.5-minute topographic quadrangle map.
Glacial deposits - some stratified deposits have been modified (including, but not limited to, extention beneath water bodies and postglacial deposits).
Glacial deposits - some stratified deposits have been modified (including, but not limited to, extention beneath water bodies and postglacial deposits).
glacial deposits
glacial deposits
glacial deposits
glacial deposits
glacial deposits
glacial deposits
glacial deposits
glacial deposits
glacial deposits
Paper copies of the published surficial geologic maps (15 quadrangles) were scanned at 500 dpi and georeferenced using lat/long coordinates (2nd-order polynomial transformation). Images were projected to UTM, zone 19, NAD27.
MassGIS
Executive Office of Environmental Affairs
251 Causeway St., Suite 500
The Office of the Massachusetts State Geologist vectorized the georeferenced images in order to digitally retain the original line work of the published maps (Mabee and others, 2004). Digital geologic map units were compiled and grouped into basic units and attributed: artificial fill, swamp deposits, floodplain alluvial deposits, stream terrace deposits, glacial stratified deposits, glacial till, and bedrock areas (outcrops and areas of shallow bedrock).
Department of Geosciences
University of Massachusetts
611 North Pleasant St.
Basic unit coverages for each layer in each quadrangle were projected to Massachusetts state plane NAD83, then edited, edge-matched, and appended into a single layer for each geologic unit (covering all published quadrangles).
101 Pitkin St.
Unpublished field sheets were scanned and georeferenced. Published map were consulted and geologic units were vectorized or created (on screen digiziting). Basic unit coverages for each layer in each quad were edited, edge-matched, and appended into a single layer for each geologic unit (covering all unpublished quadrangles).
101 Pitkin St.
Basic unit coverages for unpublished and published areas were edge-matched, edited as needed, and appended into coverages for the twenty four quadrangle area. Coverages were converted to shapefile format and combined into the four final layers.
101 Pitkin St.
Internal feature number.
ESRI
Feature geometry
ESRI
map unit label
compiler
floodplain alluvium
artificial fill
swamp deposits
map unit
compiler
Sand, gravel, silt, and some organic material, stratified and well sorted to poorly sorted, beneath the floodplains of modern streams. The texture of alluvium commonly varies over short distances both laterally and vertically, and generally is similar to the texture of adjacent glacial deposits. Along smaller streams, alluvium is commonly less than 5 ft thick. The most extensive deposits of alluvium on the map are along the Connecticut, Deerfield, Westfield, and Chicopee Rivers, where the texture is predominantly sand, fine gravel, and silt, and total thickness is as much as 25 ft. Alluvium typically overlies thicker glacial stratified deposits
compiler
Earth materials and manmade materials that have been artificially emplaced, primarily in highway and railroad embankments, and in dams; may also include landfills, urban development areas, and filled coastal wetlands
compiler
Organic muck and peat that contain minor amounts of sand, silt, and clay, stratified and poorly sorted, in kettle depressions or poorly drained areas. Swamp deposits are shown only where they are estimated to be at least 3 ft thick. Most swamp deposits are less than 10 ft thick. Swamp deposits overlie glacial deposits or bedrock. They locally overlie glacial till even where they occur within thin glacial meltwater deposits
compiler
Although this data set has been used by the U.S. Geological Survey and the Commonwealth of Massachusetts, neither the U.S. Geological Survey nor the United States Government nor the Commonwealth of Massachusetts makes any warranty, expressed or implied, nor assumes any legal liability or responsibility for the accuracy of these data or related materials.
101 Pitkin St.