The Villa Rica Gneiss Member of the Mud Creek Formation of the New Georgia Group is here named in the Villa Rica antiform on the northwest flank of the Austell-Frolona antiform in west-central GA. It consists of biotite-quartz-plagioclase gneiss with minor muscovite and epidote and is interpreted to be a felsic metavolcanic metadacite. Interlayered with the Cedar Lake Quartzite Member of the Mud Creek. Grades into stratigraphically overlying Andy Mountain and Bill Arp Formations of the informal Roosterville group. Age is Proterozoic(?).

Source: GNU records (USGS DDS-6; Reston GNULEX).

The Villa Rica Gneiss Member of the Mud Creek Formation of Abrams and McConnell (1981), is here revised as the Villa Rica Gneiss and approved for use by the USGS. It is a trondhjemite body in the Ropes Creek thrust sheet in western GA. Age is mostly Cambrian.

Source: GNU records (USGS DDS-6; Reston GNULEX).

Age of Villa Rica Gneiss of the allochthonous assemblage is changed to Late Proterozoic(?) to Middle Ordovician(?) based on a more conservative theory that the allochthonous rocks are 1) probably not older than Late Proterozoic because they are not part of Middle Proterozoic (Grenvillian) basement and 2) they could be as young, but not younger than, the time marking the beginning of closure of the ocean they originated in, as set by the slope reversal marked by deposition of Middle Ordovician Rockmart Slate upon unconformity at top of Upper Cambrian to Middle(?) Ordovician Knox Group and Middle Ordovician Lenoir Limestone.

Source: GNU records (USGS DDS-6; Reston GNULEX).