Surficial Aquifer Texture

Surficial Aquifer Texture Map was prepared from the Surficial Materials Map of Connecticut (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) to describe unconsolidated areas of the subsurface with similar properties relative to ground water flow. Surficial aquifers are unconsolidated geologic deposits capable of yielding a sufficient quantity of groundwater to wells. Surficial aquifer textures were identified from original surficial materials mapping for use in ground water applications. These are qualitative interpretations of material properties relative to ground water flow. Surficial aquifer texture groups were identified to represent aquifer textures with similar hydraulic conductivities. Some interpretations were made beneath postglacial alluvium and swamp deposits. Alluvium without a subsurface interpretation was classified as having similar hydrologic properties as till. Alluvium areas with subsurface interpretations of fines or coarse grained deposits were classified as having the hydrologic characteristics of the underlying deposits. The aquifer textures include areas of till, fine grained, fine overlying coarse grained, coarse grained, coarse overlying fine grained deposits, artificial fill, beach, salt marsh, swamp, and water. Aquifer texture groups include areas of fine grained , fine overlying coarse grained, coarse grained, and coarse overlying fine grained deposits. Surficial materials not included in the surficial aquifer texture groups include till, artificial fill, beach, salt marsh, swamp, and water. All textural terms follow the grain size classification of Stone et al 1992, modified from Wentworth, 1922. The surficial aquifer texture classifications are suitable for use at 1:24,000 scale.
Original mapping of the Surficial Materials Map of Connecticut is preserved as polygon attribute values in this data layer, and is herein described. The Surficial Materials Map of Connecticut 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, &quot;stacked&quot; 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. This map was compiled at 1:24,000 scale, and published at 1:125,000 scale.
Connecticut Surficial Materials is a 1:24,000-scale, polygon and line feature-based layer describing the unconsolidated glacial and postglacial deposits of Connecticut in terms of their grain-size distribution (texture) as compiled at 1:24,000 scale for the Surficial Materials Map of Connecticut. Glacial meltwater deposits (stratified deposits) are particularly emphasized because these sediments are the major groundwater aquifers in the State and are also the major source of construction aggregate. These deposits are described in terms of their subsurface distribution of textures as well as their extent. The texture of meltwater deposits through their total vertical thickness in the subsurface is shown to the extent that it is known or can be inferred. In some places o