Porcupine Volcanics; Rhyolite

Porcupine Volcanics; Rhyolite
State Michigan
Name Porcupine Volcanics; Rhyolite
Geologic age Middle Proterozoic
Lithologic constituents
Major
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Flow)
Comments Previously called the "unnamed formation", including on paper map of Sims (1992). The unit symbol on that map is "Yu". This has been replaced by the naming the unit, the Porcupine Volcanics, and using the symbol "Ypv", or, as in the case here, "Ypr" for the rhyolite members of the Porcupine Volcanics.
References
NGMDB product
Counties Gogebic - Ontonagon