title: Ancient Granite Gneiss in the Black Hills, South Dakota.
abstract: Granite gneiss, with an age of approximately 2.5 billion years, in the Black Hills, South Dakota, provides a link between ancient rocks in western Wyoming and Montana and in eastern North and South Dakota and Minnesota. The discovery suggests that early Precambrian rocks covered an extensive area in northcentral United States and were not restricted to several small nuclei.
authors.forename: R E
authors.initials: RE
authors.lastname: Zartman
authors.forename: J J
authors.initials: JJ
authors.lastname: Norton
authors.forename: T W
authors.initials: TW
authors.lastname: Stern