Potassium-Argon Age of Devils Tower, Wyoming

@article{Bassett1961PotassiumArgonAO,
  title={Potassium-Argon Age of Devils Tower, Wyoming},
  author={William A. Bassett},
  journal={Science},
  year={1961},
  volume={134},
  pages={1373 - 1373}
}
Devils Tower consists of columnar phonolite porphyry which contains large phenocrysts of orthoclase. Potassiumargon determinations on the orthoclase indicate an age of 40.5 million years � 4 percent. This is consistent with the geologically accepted Tertiary age. 
3 Citations
Evidence for Late Tertiary Volcanic Activity in the Northern Black Hills, South Dakota
Rhyolitic volcanic rock in the northern Black Hills has a potassium-argon isotopic age of 10.5 � 1.5 million years. This is considerably younger than any previously reported igneous activity in this
URANIUM IN ALKALINE ROCKS
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References

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This work was supported by U.S. Public Health Service research grant No. RG 7494. References and Notes
    The work reported here was conducted under the auspices of the U.S. Atomic Energy Commission
      The constants Xe and x8, were calculated from radiochemical data by