The Connecticut Quaternary Geology digital spatial data combines the information portrayed on the on-land portion of the Quaternary Geologic Map of Connecticut and Long Island Sound Basin (Stone and others 2005) with the information portrayed on its sister map, the Surficial Materials Map of Connecticut (Stone and others, 1992).  When used together, these maps provide a three dimensional context for understanding and predicting the internal composition, resource potential and hydrologic character of Connecticut's glacial and postglacial deposits. Both were compiled at 1:24,000 scale, and published at 1:125,000 scale.

The Quaternary Geologic Map of Connecticut and Long Island Sound Basin (Stone and others, 2005) portrays the glacial and postglacial deposits of Connecticut (including Long Island Sound) with an emphasis on where and how they were emplaced. Glacial Ice-Laid Deposits (thin till, thick till, and deposits of individual end moraines), Early Postglacial Deposits (Late Wisconsinan to Early Holocene stream terrace and inland dune deposits) and Holocene Postglacial Deposits (alluvium, swamp deposits, marsh deposits, beach and dune deposits, talus, and artificial fill) are differentiated from Glacial Meltwater Deposits. This mapping is based on the concept of systematic northward retreat of the Late Wisconsinan glacier.  Meltwater deposits are divided into six depositional system categories (Deposits of Major Ice-Dammed Lakes, Deposits of Major Sediment-Dammed Lakes, Deposits of Related Series of Ice-Dammed Ponds, Deposits of Related Series of Sediment-Dammed Ponds, Deposits of Proximal Meltwater Streams, and Deposits of Distal Meltwater Streams) based on the arrangement and character of the groupings of sedimentary facies (morphosequences).

The Surficial Materials Map of Connecticut (Stone and others, 1992) portrays the glacial and postglacial deposits of Connecticut in terms of their aerial extent and subsurface textural relationships. Glacial Ice-Laid Deposits (thin till, thick till, end moraine deposits) and Postglacial Deposits (alluvium, swamp deposits, marsh deposits, beach deposits, talus, and artificial fill) are differentiated from Glacial Meltwater Deposits. The meltwater deposits are further characterized using four texturally-based map units (g = gravel, sg = sand and gravel, s = sand, and f = fines). In many places a single map unit (e.g. sand) is sufficient to describe the entire meltwater section.  Where more complex stratigraphic relationships exist, "stacked" map units are used to characterize the subsurface (e.g. sg/s/f - sand and gravel overlying sand overlying fines). Where postglacial deposits overlie meltwater deposits, this relationship is also described (e.g. alluvium overlying sand). Map unit definitions (Surficial Materials Polygon Code definitions, found in the metadata) provide a short description of the inferred depositional environment for each of the glacial meltwater map units.

The geologic contacts between till and meltwater deposits coincide on both the Quaternary and Surficial Materials maps, as do the boundaries of polygons that define areas of thick till, alluvium, swamp deposits, marsh deposits, beach and dune deposits, talus, and artificial fill. Within the meltwater deposits, a Quaternary map unit (deposit) may contain several Surficial Materials textural units (akin to facies within a delta, for example). Combining the textural and vertical stacking information from the Surficial Materials map with the orderly portrayal of morphosequence relationships, up and down valley, that can be gleaned from the Quaternary map provides a three dimensional predictive context for relating the geologic setting of Connecticut's glacial meltwater deposits to their behavior as aquifers and/or transmitters of contaminants.

Since this data layer is a polygon and line feature representation of the two maps combined, each map unit's depiction and description could provide information as to its aerial extent, subsurface textural characteristics, depositional and paleogeographic settings, and facies composition in a morphosequence context. Therefore, a typical meltwater polygon would have a combination of Quaternary (e.g. Deposit of Major Sediment-Dammed Lake; Glacial Lake Middletown Cromwell Deltaic Deposit) and Surficial Materials (e.g. sand and gravel overlying sand overlying fine) map attributes.  Additional polygon features are incorporated to define surface water areas for streams, lakes, ponds, bays, and estuaries greater than 5 acres in size. Line features describe the type of boundary between individual geologic or textural units such as a geologic contact line between two different geologic units or a linear shoreline feature between a textural unit and an adjacent waterbody.

The data have been updated to reflect minor changes in map unit name (QUPOLY_COD) for consistency with the 2005 publication of the Quaternary Geologic Map of Connecticut and Long Island Sound Basin. Previously distributed versions of CTQSGEOM were consistent with the 1998 Open-file Report for the same map.

It is important to note that this data layer represents only the on-land portion of the Quaternary Geologic Map of Connecticut and Long Island Sound Basin (Stone and others, 2005). The off-shore geologic units are organized in separate data layers (LISQMOR, LISQFAN, LISQLAKE, LISQCHAN, LISQMARD) which can be used in conjunction with this data layer. These Long Island Sound layers have been mapped at 1:80,000 scale using seismic reflection data.

The CTQSGEOM data layer should be used as the geologic base for Connecticut Quaternary Geology / Surficial Materials Features (CTQSFEAT) data layer which represents features such as eskers, meltwater channels, spillways, and locations of radio-carbon dated samples.

Connecticut Quaternary Geology and Surficial Materials is 1:24,000-scale data suitable for geologic and environmental mapping and analysis purposes. Not intended for maps printed at map scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet.). Not intended for analysis with other digital data compiled at scales greater than or more detailed than 1:24,000 scale. This data layer should be used as the geologic base for Connecticut Quaternary Geology / Surficial Materials Features (CTQSFEAT). The data layer can be used in conjunction with data layers representing related geologic features in the Long Island Sound Basin (LISQMOR, LISQFAN, LISQLAKE, LISQCHAN, LISQMARD).

Data manually digitized from 1:24,000-scale mylar quadrangle compilation sheets prepared for the Surficial Materials Map of Connecticut, 1:125,000 scale (Stone and others, 1992) and the Quaternary Geologic Map Of Connecticut and Long Island Sound Basin, 1:125,000 scale (Stone and others,2005).  For a more complete understanding of the geologic principles behind the data it is advisable to consult these source maps which contain cross sections, diagrams and text not available in digital form.  Digital files which should be used with this data set include: SIM-2784.pdf (pamphet from the Quaternary Geologic Map Of Connecticut and Long Island Sound Basin), Surficial Materials data layer, and the companion data sets: Connecticut Quaternary Geology / Surficial Materials Features (CTQSFEAT), and Long Island Sound moraines (LISQMOR), lacustrine fans (LISQFAN), lake-bottom and deltaic deposits (LISQLAKE), channel-fill deposits (LISQCHAN), and marine deltaic deposits (LISQMARD); all available for download at http://www.dep.state.ct.us/gis.

Kristi LeDuc, Margaret Thomas, and Mary DiGiacomo-Cohen for designing, compiling, digitizing, and editing the Quaternary Geology and Surficial Materials data layer. Much of the production effort was undertaken by the Long Island Sound Resource Center: a partnership between the State of Connecticut, Department of Environmental Protection and the University of Connecticut Marine Sciences and Technology Center. This digital data was produced by the State of Connecticut, Department of Environmental Protection with support from the U.S. Geological Survey, the U.S. Environmental Protection Agency, and the Connecticut Department of Public Health and Addiction Services. The U.S. Geological Survey in cooperation with the State of Connecticut, Department of Environmental Protection, Geological and Natural History Survey drafted the 1:24,000-scale compilation sheets used to publish the 1:125,000-scale Surficial Materials Map of Connecticut, Stone and others, 1992 and create the 1:24,000-scale digital data.

publication date

None. The data is in the public domain and may be redistributed.

No restrictions or legal prerequisites for using the data. The data is suitable for use at appropriate scale, and is not recommended for use with other data layers having source map scales greater than 1:24,000 (1 inch = 2000 feet) or printed on maps at scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet). The geologic contacts are considered accurate as mapped at 1:24,000 scale. While it may be desirable to represent the geology at a larger scale for site-specific applications, keep in mind that 1:24,000-scale accuracy may not be appropriate for such uses. Although this data set has been used by the State of Connecticut, Department of Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Environmental Protection as to the accuracy of the data and 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 State of Connecticut, Department of Environmental Protection 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 is distributed to the user, modifications made to the data by the user should be noted in the metadata. When printing this data on a map or using it in a software application, analysis, or report, please acknowledge the U.S. Geological Survey and the State of Connecticut, Department of Environmental Protection as the source for this information. For example, include the following data source description when printing this layer on a map: Quaternary Geology - From the Quaternary Geology/Surficial Materials Master layer, compiled and published by the USGS and CT DEP. Source map scale is 1:24,000. The data is most relevent when used at the intended state-wide scale of 1:125,000 and in conjunction with the additional information found only on the following parent maps: Surficial Materials Map of Connecticut (Stone and others, 1992) and Quaternary Geologic Map of Connecticut and Long Island Sound Basin (Stone and others, 2005).

Polygon codes Surficial Materials unit (SMPOLY_COD), Quaternary Geologic unit (QUPOLY_COD), and Depositional System (DSPOLY_COD) represent the underlying classification scheme for units completely named in their respective de-code fields and described further in this metatdata document, Surficial Materials metadata, and SIM_2784.pdf (pamplet for the Quaternary map, Stone and others, 2005). These text files have been excerpted from the text on sheet 1 of the Surficial Materials Map of Connecticut and in the pamphlet of the Quaternary Geologic Map of Connecticut and Long Island Sound Basin. They have been modified as necessary for use with the 1:24,000 scale digital data, and are not considered as valid substitutes for the information found on the published maps.

Line features describe the boundary between textural (surficial material) and/or geologic units, such as a contact between two different materials units, or a shoreline feature between a geologic unit and an adjacent waterbody, or the state boundary.

U.S. Geological Survey and State of Connecticut, Department of Environmental Protection

Polygon features conform to the following topological rules. Polygons are single part. There are no duplicate polygons. Polygons do not self overlap. Polygons do not overlap other polygons. Lines are single part. Line features conform to the following topological rules. There are no duplicate lines. Lines do not self overlap. Lines do not overlap other lines. Lines intersect only at nodes, and nodes anchor the ends of all lines. Lines do not overshoot or undershoot other lines they are supposed to meet and intersect. In general, there are no duplicate features, unresolved intersections, overshooting lines, open polygons, sliver polygons, or unlabeled (unattributed) polygons. The tests of logical consistency were performed by the State of Connecticut using ESRI ArcInfo software to maintain feature topology in ArcInfo coverage format. The data is topologically clean. The ArcInfo Clean function was repeatedly used following edits to verify topology and enforce a minimum distance between vertices of 4 feet (fuzzy tolerance) and a minimum allowed overshoot length of 0 feet (dangle length).

The data reflects the content of the data source, which is a set of 1:24,000 scale mylar sheets used to compile and publish the Surficial Material Map of Connecticut, Stone and others, 1992 (U.S. Geological Survey in cooperation with the Connecticut Geological and Natural History Survey, DEP, 2 sheets, 1:125,000 publication scale), and the Quaternary Geologic Map of Connecticut and Long Island Sound Basin, Stone and others, 2005 (U.S. Geological Survey in cooperation with the Connecticut Geological and Natural History Survey, DEP, 2 sheets, 1:125,000 publication scale).   The datalayer was digitized from these 1:24,000-scale mylar compilation sheets. This datalayer (QUPOLY_COD - Quaternary Map unit label abbreviations) was updated to reflect minor editorial comments relating to the 2005 publication of the Quaternary Geologic Map of Connecticut and Long Island Sound Basin. All 116 Connecticut quadrangles of mapped on-land Quaternary and surficial materials units have been digitized and included in this data layer; all off-shore Quaternary units have been digitized as a separate effort and are available as separate data layers (LISQMOR, LISQLAKE, LISQFAN, LISQCHAN, LISQMARD).

The Quaternary Geology/Surficial Materials layer retains the feature types and information identified on the 1:24,000-scale compilation sheets used for both the Surficial Materials Map of Connecticut, Stone and others, 1992 and the Quaternary Geologic Map of Connecticut and Long Island Sound Basin. All attributes have valid values. Values are within defined domains. The accuracy test for the SMPOLY_COD and QUPOLY_COD attribute values was conducted by comparing the geologic map unit information presented on the source mylar overlays with 1:24,000-scale check plots or interactive displays of the digital data on a computer graphic system. These check plot maps and computer displays depicted and labeled the polygon features in different colors and line-fill patterns based on SMPOLY_COD and QUPOLY_COD attribute values for comparison with the original data source. SURFM_POLY and SM_DESC represent both brief and full text English language equivalents of (decodes) the SMPOLY_COD attribute, respectively. The AV_LEGEND and IMS_LEGEND polygon attributes are based on and key off the QUPOLY_COD attribute. These related attributes were populated by joining to lookup data tables using the SMPOLY_COD as the relate key field instead of manually entering these values for each polygon feature. These lookup data tables contain records that account for and describe the unique occurrences of SMPOLY_COD values. The AREA_SQMI (area in square miles) and ACREAGE (area in acres) field were automatically calculated for each polygon feature based on computer generated feature area in square feet. For line features, the QSARC_COD attribute that distinguishes contact boundaries from shoreline boundaries was manually entered for each feature.

The horizontal positional accuracy of this 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. Feature locations were interpolated from the transporation features, surface water features, elevation contours, buildings,  built-up areas, and other natural features and landforms depicted on USGS 7.5 minute topographic quadrangle maps.

Conforms with Connecticut DEP Spatial Data Standards.  Standards for feature accuracy are: 90 percent of the digitized features are within .01 inch of the centerline of that feature on the manuscript (original map); 100 percent of all features must be within .02 inch. There are no duplicate features, unresolved intersections, overshooting arcs, open polygons, sliver polygons, or unlabeled polygons. Fuzzy and Dangle Tolerances were verified and set in the ArcInfo coveage tolerance (TOL) file.

Connecticut Quaternary Geology and Surficial Materials Line

Although this data set  has been used by the State of Connecticut, Department of Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Environmental Protection as to the accuracy of the data and or related materials.  The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the State of Connecticut, Department of Environmental Protection 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 is distributed to the user, modifications made to the data by the user should be noted in the metadata.

Geographic information sytem (GIS), computer-aided drawing or other mapping software is necessary to display, view and access the information.

The data distributor does not provide custom GIS analysis or mapping services. Data is available in a standard format and may be converted to other formats, projections, coordinate systems, or selected for specific geographic regions by the party receiving the data.