Piegan Group.

Calcareous and dolomitic siltite, quartzite, and subordinate argillite of the Helena and Wallace formations in northern Idaho; south of St. Joe River, correlative rocks include garnet grade feldspathic quartzite and calc-silicate gneiss. (Mesoproterozoic Belt Supergroup).
State Idaho
Name Piegan Group.
Geologic age Mesoproterozoic
Lithologic constituents
Metamorphic > Metasedimentary > Metaclastic > MetasiltstoneCalcareous and dolomitic siltite.
Metamorphic > Metasedimentary > Metaclastic > QuartziteQuartzite and garnet grade feldspathic quartzite.
Metamorphic > Gneiss > Calc-silicate-gneiss
Metamorphic > Metasedimentary > Metaclastic > Argillite

Lewis, Reed S., Link, Paul K., Stanford, Loudon R., and Long, Sean P., Geologic Map of Idaho, 2012, Idaho Geological Survey, Geologic Map 9 (M-9); Scale 1:500,000.

NGMDB product
Counties Benewah - Bonner - Boundary - Clearwater - Idaho - Kootenai - Latah - Shoshone