Millboro Shale and Needmore Formation (VADmn;0)

State	Virginia
Name	Millboro Shale and Needmore Formation
Geologic age	Devonian
Original map label	Dmn
Comments	Appalachian Plateaus and Valley and Ridge. From expanded explanation (ref. VA002): Millboro Shale and Needmore Formation. Millboro Shale (Cooper, 1939; Butts, 1940). Shale, black, fissile, pyritic, with septarian concretions locally, gradational with underlying Needmore Shale; present southwest of Shenandoah County except in southwesternmost Virginia; thickness is as much as 1000 feet in north-central western Virginia. Laterally equivalent to the Marcellus Shale and Mahantango Formation to the north east and the lower part of the Chattanooga Shale to the southwest. It is gradational with the underlying Needmore Formation. Needmore Formation. Refer to description under Dmrn.
Primary rock type	black shale
Secondary rock type	shale
Other rock types	bentonite; limestone
Lithologic constituents	Major Sedimentary > Clastic > Mudstone > Shale > Black-shale (Calcareous) Sedimentary > Clastic > Mudstone > Shale Incidental Sedimentary > Carbonate > Limestone (Calcareous) Sedimentary > Clastic > Mudstone > Claystone > Bentonite
Map references	Digital Representation of the 1993 Geologic Map of Virginia", 2003, CD ROM (ISO-9660) contains image file, expanded explanation in pdf, and ESRI shapefiles, viewing software not included. This is a digital version of "Geologic Map of Virginia" published in 1993. Available from: https://www.dmme.virginia.gov/commerce/ [https://www.dmme.virginia.gov/commerce/]
Unit references	Virginia Division of Mineral Resources, 1993, Geologic Map of Virginia: Virginia Division of Mineral Resources, scale 1:500,000 Digital Representation of the 1993 Geologic Map of Virginia - expanded explanation: 2003, Commonwealth of Virginia, Department of Mines, Minerals, and Energy, Divsion of Mineral Resources, Publication 147, 85 pp Digital Representation of the 1993 Geologic Map of Virginia", 2003, CD ROM (ISO-9660) contains image file, expanded explanation in pdf, and ESRI shapefiles, viewing software not included. This is a digital version of "Geologic Map of Virginia" published in 1993. Available from: https://www.dmme.virginia.gov/commerce/ [https://www.dmme.virginia.gov/commerce/]
Geographic coverage	Alleghany - Augusta - Bath - Botetourt - Craig - Giles - Highland - Montgomery - Pulaski - Roanoke - Rockbridge - Rockingham - Shenandoah - Covington - Radford - Roanoke