Ancient Granite Gneiss in the Black Hills, South Dakota

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Science  31 Jul 1964:
Vol. 145, Issue 3631, pp. 479-481
DOI: 10.1126/science.145.3631.479


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