Lynchburg Group; Monumental Mills Formation

Monumental Mills Formation (Wehr, 1985). Lightgray, fine- to very-fine-grained metasandstone characterized by thin planar beds separated by biotite-rich silty partings; and dark-gray laminated siltstone and mudstone containing abundant synsedimentary deformation features including folds, faults, convolute bedding, and erosional-depositional discordances. Mineralogy: quartz + albite + mu covite + biotite + epidote + calcite + chlorite + titanite + magnetite ± garnet ± pyrite; porphyroblastic garnet and biotite are common. The Monumental Mills has been interpreted to represent deposition in a delta front-slope environment (Wehr, 1985).
State Virginia
Name Lynchburg Group; Monumental Mills Formation
Geologic age Proterozoic Z
Lithologic constituents
Major
Metamorphic > Metasedimentary > Metaclastic > Metasandstone
Minor
Metamorphic > Metasedimentary > Metaclastic > Metasiltstone
Sedimentary > Clastic > Mudstone
Comments Lynchburg Group; Blue Ridge Anticlinorium (Central)
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 Culpeper - Fauquier - Madison