Cypress Swamp Formation

GM21 Geologic Map of the Trap Pond and Pittsville Quadrangles, Delaware

The geological history of the surficial units of the Trap Pond and the Delaware portion of the Pittsville Quadrangle was the result of deposition of the Beaverdam Formation and its subsequent modification by erosion and deposition related to the sea-level fluctuations during the Pleistocene. The geology reflects this complex history by the cut and fill geometry of the Middle and late Pleistocene deposits into the Beaverdam Formation. The geology is further complicated by periglacial activity that produced dune deposits and Carolina Bays in the map area, which modified the land surface.

GM20 Geologic Map of the Millsboro and Whaleysville Quadrangles, Delaware

The geological history of the surficial units of the Millsboro Quadrangle and
Delaware portion of the Whaleysville Quadrangle was the result of deposition of the
Beaverdam Formation during the late Pliocene and its subsequent modification by
erosion and deposition related to sea-level fluctuations during the Pleistocene and late
Pleistocene upland swamp and bog deposition. The geology at the land surface was then
further modified by periglacial activity that produced dune deposits and Carolina Bays in

GM19 Geologic Map of the Frankford and Selbyville Quadrangles, Delaware

The geological history of the surficial units of the Frankford and Delaware
portion of the Selbyville Quadrangles was the result of deposition of the Beaverdam
Formation during the late Pliocene and its subsequent modification by erosion and
deposition related to sea-level fluctuations during the Pleistocene. The geology at the
land surface was then further modified by periglacial activity that produced dune deposits
in the map area. Surficial geologic mapping was conducted using field maps at a scale of

Cypress Swamp Formation

The upper part of the Cypress Swamp Formation is a multi-colored, thinly bedded to laminated, quartzose fine sand to silty fine sand, with areally discontinuous laminae to thin beds of fine to coarse sand, sandy silt, clayey silt, organic silt, and peat. The lowermost 3 to 6 ft of the unit are commonly composed of thin beds of dark-colored, organic-rich, clayey silt with laminae to thin beds of fine sand and peat. Fine sand to fine sandy silt are present at the base of the unit in boreholes where the lower organic-rich beds are absent. Dark-colored, peaty, organic-rich silt and clayey silt with laminae of fine to medium sand as much as 4.5 ft thick are common within 5 ft of land surface, but may be absent in some locations. Colors are shades of brown, gray, and green where the unit contains visible organic matter, and orange, yellow, and red at shallow depths where the organic-rich beds are absent. Clay-sized minerals are a mixed suite that includes kaolinite, chlorite, illite, and vermiculite.

RI64 Results of Hydrogeologic Studies of the Cypress Swamp Formation, Delaware

The Cypress Swamp Formation is the surficial geologic unit in south-central Sussex County, Delaware. Detailed hydrologic observations made as part of four separate studies between 1995 and 1999 show that the Cypress Swamp Formation consists of a complex assemblage of moderately permeable sands and low permeability organic and inorganic silts and clays that form a heterogeneous shallow subsurface hydrologic system that is between about 5 and 15 feet thick. Aquifer tests show that hydraulic conductivity ranges between 0.55 and 40 ft/day, with an arithmetic mean of 13 feet/day.

RI62 The Cypress Swamp Formation, Delaware

The Cypress Swamp of Sussex County, Delaware, is underlain by a body of late Pleistocene- to Holocene-age unconsolidated sediments. They form a mappable geologic unit herein named the Cypress Swamp Formation. Deposits of the formation can be found outside the current boundaries of the Cypress Swamp and record the erosion and redistribution of older Pleistocene coastal and Pliocene sedimentary units.