Pliocene Sand and Gravel

Interbedded yellowish-orange to reddish-brown gravelly sand, sandy gravel, and fine to coarse sand, poorly to well-sorted, cross-bedded in part, in cludes lesser amounts of clay and silt in thin to medium beds. Commonly caps drainage divides (altitude 250-170 feet) in western part of Coastal Plain. Lower part of unit, showing flaser and lenticular bedding and containing rare to abundant Ophiomorpha nodosa represents deposition in marginal-marine environments and is, in part, a nearshore equivalent of the more downdip, marine facies of the Yorktown Formation. In the northern part of the Coastal Plain, the more poorly sorted and less cleanly washed upper part of unit, which lacks fossils, comprises fluvial-deltaic sediments that prograded eastward across the shelf during a regressive phase of the Yorktown. To the south, the upper part of unit is massively bedded clayey sand in places containing heavy mineral concentrations that average 8 percent or more; the sands are nearshore, beach and dune origin; interstitial clay was derived, in part, from in-situ weathering of feldspar sand. Thick ness is 0 to 50 feet.
State Virginia
Name Pliocene Sand and Gravel
Geologic age Tertiary
Lithologic constituents
Major
Unconsolidated > Coarse-detrital > Gravel
Unconsolidated > Coarse-detrital > Sand
Minor
Unconsolidated > Fine-detrital > Clay
Unconsolidated > Fine-detrital > Silt
Comments Coastal Plain
References

Virginia Division of Mineral Resources, 1993, Geologic Map of Virginia: Virginia Division of Mineral Resources, scale 1:500,000.

Virginia Division of Mineral Resources, 2003, Digital Representation of the 1993 Geologic Map of Virginia, Publication 174, CD ROM (ISO-9660) contains image file, expanded explanation in pdf, and ESRI shapefiles, scale 1:500,000.

NGMDB product
Counties Arlington - Brunswick - Caroline - Chesterfield - Dinwiddie - Essex - Fairfax - Greensville - Hanover - Henrico - King George - King William - New Kent - Richmond - Spotsylvania - Stafford - Sussex - Westmoreland - Alexandria - Fredericksburg - Richmond