Beaverdam FormationBeaverdam Formation johncallahan Mon, 07/27/2009 - 13:45
The following description was published in GM15 Geologic Map of the Georgetown Quadrangle, Delaware, Ramsey, K.W., 2010:
Heterogeneous unit ranging from very coarse sand with pebbles to silty clay. Predominant lithologies at land surface are white to mottled light-gray and reddish-brown, silty to clayey, fine to coarse sand. Laminae and beds of very coarse sand with pebbles to gravel are common. Laminae and beds of bluish-gray to light-gray silty clay are also common. In a few places near land surface, but more commonly in the subsurface, beds ranging from 2- to 20-ft thick of finely laminated, very fine sand and silty clay are present. The sands of the Beaverdam Formation commonly have a white silt matrix that gives drill cuttings a milky appearance (Ramsey, 2001, 2007). This white silt matrix is the most distinguishing characteristic of the unit and readily differentiates the Beaverdam Formation from the adjacent clean sands of the Turtle Branch Formation. Interpreted to be a fluvial to estuarine deposit of late Pliocene age on the basis of pollen assemblages and regional stratigraphic relationships (Andres and Ramsey, 1995a, 1996; Groot and Jordan, 1999; Groot et al., 1990). Ranges from 50 to 120 ft thick in the Georgetown Quadrangle.
The following description was published in GM14 Geologic Map of Kent County, Delaware, Ramsey, K.W., 2007:
Light gray to white coarse to very coarse sand with beds of fine to medium sand. Sands are quartzose, moderately feldspathic (
Coastal Plain - Primarily Surficial Unit
Andres, A.S., and Ramsey, K.W., 1995a, <a href="/publications/gm9-geology-seaford-area-delaware">Geology of the Seaford area, Delaware: Delaware Geological Survey Geologic Map No. 9</a>, scale 1:24,000.
_____, 1995b, <a href="/publications/ofr39-basic-data-geologic-map-seaford-area-delaware">Basic data for the geologic map of the Seaford area, Delaware: Delaware Geological Survey Open File Report 39</a>, 39 p.
_____, 1996, <a href="/publications/ri53-geology-seaford-area-delaware">Geology of the Seaford area, Delaware: Delaware Geological Survey Report of Investigations No. 53</a>, 22 p.
Groot, J.J., Ramsey, K.W., and Wehmiller, J.F., 1990, <a href="/publications/ri47-ages-bethany-beaverdam-and-omar-formations-southern-delaware">Ages of the Bethany, Beaverdam, and Omar formations of southern Delaware: Delaware Geological Survey Report of Investigations No. 47</a>, 41 p.
Groot, J.J., and Jordan, R.R., 1999, <a href="/publications/ri58-pliocene-and-quaternary-deposits-delaware-palynology-ages-and-paleoenvironments">The Pliocene and Quaternary deposits of Delaware: palynology, ages, and paleoenvironments: Delaware Geological Survey Report of Investigations No. 58</a>, 19 p.
Ramsey, K. W., 2001, <a href="/publications/gm11-geology-ellendale-and-milton-quadrangles-delaware">Geologic map of the Ellendale and Milton quadrangles, Delaware: Delaware Geological Survey Geologic Map Series No. 11</a>, scale 1:24,000.
_____, 2007, <a href="/publications/gm14-geologic-map-kent-county-delaware">Geologic Map of Kent County, Delaware: Delaware Geological Survey Geologic Map Series No. 14</a>, scale 1:100,000.