| Early postglacial deposits of the Heath-Northfield-Southwick-Hampden 24-quadrangle area in the Connecticut Valley region, west-central Massachusetts - early_postglacial | |
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Data format: Shapefile File or table name: early_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 early_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 early_postglacial layer shows areas of alluvial fan deposits, stream-terrace deposits, inland dune deposits, and talus deposits for a twenty-four-quadrangle area in west-central Massachusetts. This data layer should be used in conjunction with the underlying till_bedrock and stratified_deposits data layers, and the overlying the postglacial data layer. |
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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 early_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 early_postglacial layer shows areas of alluvial fan deposits, stream-terrace deposits, inland dune deposits, and talus deposits for a twenty-four-quadrangle area in west-central Massachusetts. This data layer should be used in conjunction with the underlying till_bedrock and stratified_deposits data layers, and the overlying the postglacial data layer.
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 early_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 early_postglacial layer shows areas of alluvial fan deposits, stream-terrace deposits, inland dune deposits, and talus deposits for a twenty-four-quadrangle area in west-central Massachusetts. This data layer should be used in conjunction with the underlying till_bedrock and stratified_deposits data layers, and the overlying the postglacial data layer. 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. 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 early 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.
Metadata imported.
Internal feature number.
ESRI
Feature geometry
ESRI
map unit label
compiler
alluvial fan deposits
stream-terrace deposits
inland dune deposits
talus deposits
map unit
compiler
Generally coarse gravel and sand deposits on steep slopes where high-gradient streams entered lower-gradient valleys. Some alluvial fans in this area were graded to lowering levels of glacial Lake Hitchcock. Some fans continue to form today
compiler
Sand, gravel, and silt deposited by meteoric water (locally distal meltwater) on terraces cut into glacial meltwater sediments along rivers and streams. Most stream-terrace deposits are less than 10 ft thick and overlie thicker glacial deposits; textures are usually similar to underlying glacial meltwater deposits. Many stream terraces in the Connecticut River valley are composed of fine to medium sand and overlie lake-bottom silt and clay
compiler
Fine to medium, well-sorted sand in transverse, parabolic, and hummocky dunes as much as 60 ft thick. Deposits occur chiefly in the glacial Lake Hitchcock basin where sand derived from extensive glacial-lake deltas that were not yet vegetated was deposited in dune forms by early postglacial winds. Dune sand is now fixed by vegetation except where disturbed by human activities
compiler
Angular, loose blocks of basalt and diabase accumulated by rockfall and creep at the base of bedrock cliffs along linear traprock ridges in the Mesozoic lowland. Talus deposits form steep, unstable slopes. Generally less than 20 ft thick
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.