Connecticut Surficial Materials is 1:24,000-scale data that describes the unconsolidated glacial and postglacial deposits of Connecticut in terms of their grain-size distribution (texture). This information portrays the areal extent and grain-size (textural) distributions of surficial material deposits such as glacial till, end moraines, fines (silt and clay), sand, gravel, floodplain alluvium, swamp deposits, salt marsh deposits, talus, and artificial fill. The map legend highlights the relationship between the depositional origins and the distribution and character of Connecticut surficial material deposits. These deposits range from a few feet to several hundred feet in thickness, overlie the bedrock surface and underlie the organic soil layer of Connecticut. Surficial Materials are mapped without regard for any organic soil layer that may overly the deposit. Surficial materials were emplaced in Connecticut during the Quaternary Period, which spans from 2.588 ± 0.005 million years ago to the present and includes the Pleistocene (glacial) and Holocene (postglacial) Epochs.
The Connecticut Surficial Materials information was initially compiled at 1:24,000 scale (1 inch = 2,000 feet) then recompiled for a statewide 1:125,000-scale map, the Surficial Materials Map of Connecticut (PDF, 26 Mb), Stone, J.R., Schafer, J.P., London, E.H., DiGiacomo-Cohen, M.L., Lewis, R.L., and Thompson, W.B., 2005, U.S. Geological Survey Scientific Investigation Map 2784, 2 sheets, scale 1:125,000. A companion map, the Quaternary Geology Map of Connecticut and Long Island Sound Basin (PDF, 56 Mb), Stone, J.R., Schafer, J.P., London, E.H. and Thompson, W.B., 1992, U.S. Geological Survey Special Map, 2 sheets, scale 1:125,000, and pamphlet, 71 p emphasizes the geologic history and the distribution of depositional environments during the emplacement of unconsolidated glacial and postglacial surficial deposits and the landforms resulting from those events. The quaternary geology and surficial material features portrayed on these two maps are very closely related; each contributes to the interpretation of the other.
For additional documentation including a description of the map legend for Surficial Materials, refer to the CT ECO Complete Resource Guide for Surficial Materials.
Surficial Materials is 1:24,000-scale data suitable for geologic and environmental mapping and analysis purposes. It is not intended for maps printed at map scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet). The1:24,000-scale Surficial Material features and the 1:24,000-scale Quaternary Geology features are very closely related; each contributes to the interpretation of the other. The Quaternary Geology data is complemented by the Surficial Geology data in that the grain-size distribution (texture) of individual Quaternary Geology deposits is defined and described in the Surficial Materials data. For example, the Surficial Materials data specifies the texture (grain size) for a given Quaternary Geology Sediment of Dammed Pond deposit as either comprised of Sand, Gravel, Sand and Gravel, Sand and Gravel overlying Sand, Sand overlying Sand and Gravel, Sand overlying Fines, or another similar combination. Not all Quaternary Geology deposits exhibit the same grain size.
Quaternary Geology Map of Connecticut and Long Island Sound Basin (PDF, 56 Mb) provides information the geologic history and the distribution of depositional environments during the emplacement of unconsolidated glacial and postglacial surficial deposits and the landforms resulting from those events in Connecticut, whereas the Surficial Materials Map of Connecticut (PDF, 26 Mb) emphasizes the surface and subsurface texture (grain-size distribution) of these materials.
Surficial Materials is not intended for maps printed at map scales greater or more detailed than 1:24,000 scale (1 inch = 2,000 feet). It is not intended for analysis with other digital data compiled at scales greater or more detailed than 1:24,000 scale. This information is based on 7.5 minute U.S. Geological Survey 1:24,000-scale topographic quadrangle maps with a 10-ft contour interval. Surficial geologic maps exist in various forms (either published, open-filed, or unpublished) for 98 quadrangles. The authors of the Surficial Materials Map of Connecticut reviewed all of these maps, and did reconnaissance mapping in the remaining quadrangles. In the course of compiling this large body of data to create both the statewide Surficial Materials Map and the statewide Quaternary Geology Map, the authors applied a consistent interpretive rationale; the result is that, in some cases, the original studies have been reworked or revised.