Named for exposures along and north of Fountain Road, just northeast of Mableton, GA. Named as a member of the Powers Ferry Formation. Consists of layered hornblende-plagioclase amphibolite. Higgins (1968) shows two disconnected belts of amphibolite within Powers Ferry unit, but recent work shows they are connected. Based on geologic mapping, thickness is about 500-700 m (1,640-2,300 ft). Age is late Precambrian and (or) early Paleozoic.
Source: GNU records (USGS DDS-6; Reston GNULEX).
Age of the Mableton Amphibolite Member of the Powers Ferry Formation is Late Proterozoic to Early Ordovician(?).
Source: GNU records (USGS DDS-6; Reston GNULEX).
Recent mapping has shown that rocks previously designated as Mableton Amphibolite Member of Powers Ferry Formation are actually part of Ropes Creek Metabasalt. Mableton is herein abandoned. Powers Ferry Formation is removed from Sandy Springs Group and reduced in rank to Powers Ferry Formation of Stonewall Gneiss (revised) also due to results of detailed mapping. Report includes geologic map and correlation chart.
Source: GNU records (USGS DDS-6; Reston GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).