The Reservoir Granite of Berkey and Rice (1921), mapped here as granitic gneiss, may not be all intrusive. Considerable portions may be biotitic migmatitic gneiss that only appears to be comagmatic with the true intrusive part of the unit. As the term "granite" may be misleading, it is redefined and changed to Reservoir Gneiss. Age is Middle Proterozoic.
Source: GNU records (USGS DDS-6; Reston GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
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