| Till and moraine deposits of the Pocasset-Provincetown-Cuttyhunk-Nantucket 24-quadrangle area of Cape Cod and Islands, southeast Massachusetts | |
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Data format: Shapefile File or table name: till Coordinate system: State Plane Coordinate System 1983 Theme keywords: surficial geology, stratified materials, stratified deposits, till, moraine, glacial deposits, beach, alluvium, swamp deposits, artificial fill, dune, cranberry bog |
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Abstract:
The till 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 till layer shows areas of thin till, thrust-moraine deposits, and moraine deposits for a twenty-four-quadrangle area in southeast Massachusetts. Thrust-moraine deposit polygons overlie areas of thin till; moraine polygons may overlie thrust_moraine polygons or thin till polygons. This data layer should be used in conjunction with the overlying stratified_deposits data layer and the postglacial deposits 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 till 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 till layer shows areas of thin till, thrust-moraine deposits, and moraine deposits for a twenty-four-quadrangle area in southeast Massachusetts. Thrust-moraine deposit polygons overlie areas of thin till; moraine polygons may overlie thrust_moraine polygons or thin till polygons. This data layer should be used in conjunction with the overlying stratified_deposits data layer and the postglacial deposits 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 till 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 till layer shows areas of thin till, thrust-moraine, and moraine deposits for a twenty-four-quadrangle area in southeast Massachusetts. This data layer should be used in conjunction with the overlying stratified_deposits data layer and the postglacial deposits 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 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 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.
1080 Shennecossett Rd.
Multiple agencies and individuals contributed to this data layer: MassGIS scanned and georeferenced paper copies of the published surficial geologic maps for fourteen 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 ten 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. Moraine deposits may overlie thin till and thrust moraine polygons. Thrust moraine polygons may overlie thin till 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 till and moraine 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
glacial deposits
glacial deposits
glacial deposits
glacial deposits
Paper copies of the published surficial geologic maps (10 quadrangles and Nantucket) 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, glacial stratified deposits, glacial till, and moraine deposits.
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).
1080 Shennecossett Rd.
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).
1080 Shennecossett Rd.
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 three final layers.
1080 Shennecossett Rd.
Internal feature number.
ESRI
Feature geometry
ESRI
map unit label
compiler
thin till
moraine deposits
thrust-moraine deposits
map unit
compiler
Nonsorted, nonstratified matrix of sand, some silt, and little clay containing scattered gravel clasts and few large boulders; predominantly upper till of the last glaciation; loose to moderately compact, generally sandy, commonly stony. Two facies are present in some places: a looser, coarser-grained ablation facies, melted out from supraglacial position; and an underlying more compact, finer-grained lodgement facies deposited subglacially. Both ablation and lodgement facies of upper till are sandy and stony, and derived from coarse-grained crystalline rocks. Unit includes till of probable Illinoian age beneath eastern Nantucket (Oldale and others, 1982). Beneath Cape Cod, subsurface till overlies fresh, nonweathered bedrock; this basal till varies in known thickness from <5 to >50 ft (Cotton and Koteff, 1962; Masterson and others, 1997; Folger and others, 1978; Hall and others, 1980). Till may overlie Cretaceous, Tertiary, or older Pleistocene deposits beneath the adjacent islands.
compiler
Surface deposits of nonsorted, nonstratified matrix of sand, some silt, and little clay containing scattered gravel clasts and few large boulders; predominantly till of the last glaciation; loose to moderately compact, generally sandy, commonly stony. Two facies of till are present in some places: a looser, coarser-grained ablation facies, melted out from supraglacial position; and an underlying more compact, finer-grained lodgement facies deposited subglacially. Both ablation and lodgement facies of till are stony, containing boulders, and are derived from coarse-grained crystalline rocks. The surface nonsorted deposits, 6 to 30 ft thick, overlie sand, gravel, and silty sand meltwater deposits that extend downward to basal till and bedrock. Surface deposits and stratification in underlying sediments commonly are distorted and faulted due to postdepositional collapse related to melting of buried ice.
compiler
Surface deposits of nonsorted, nonstratified matrix of sand, some silt, and little clay containing scattered gravel clasts and large boulders; predominantly till of the last glaciation; loose to moderately compact, generally sandy, commonly stony. Two facies of till are present in some places: a looser, coarser-grained ablation facies, melted out from supraglacial position; and an underlying more compact, finer-grained lodgement facies deposited subglacially. Both ablation and lodgement facies of till are stony, containing boulders, and are derived from coarse-grained crystalline rocks. In western Martha's Vineyard, thrust-moraine deposits include thin surface till and subsurface ice-thrusted beds of Tertiary fossiliferous sand, gravel, and silty clay deposits, and Pleistocene sand and silty clay beds. In eastern Nantucket, moraine deposits include thin surface till and ice-thrusted beds of sandy glacial meltwater deposits, interglacial marine sand, and older till at the base.
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 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.
1080 Shennecossett Rd.