Bigfork Chert  search
BTChronostratigraphic Units
 .Phanerozoic
 ..Paleozoic
 ...Ordovician
 ....Middle Ordovician
 .....Bigfork Chert
UFBig Fork Chert
RTOklahoma
 Texas
 Arkansas
 Ouachita Belt
SNSW Arkansas, SE Oklahoma, and Texas. Added to Thesaurus in 1995.