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Potassium-argon dates and the Cenozoic mammalian chronology of North America

Evernden, J F; Savage, D E; Curtis, G H; James, G T (1972) Potassium-argon dates and the Cenozoic mammalian chronology of North America. Miscellaneous Investigations Series - U. S. Geological Survey. 1972. .

AuthorsEvernden, J F; Savage, D E; Curtis, G H; James, G T
Year1972
TitlePotassium-argon dates and the Cenozoic mammalian chronology of North America
SourceMiscellaneous Investigations Series - U. S. Geological Survey. 1972. .
PublisherU. S. Geological Survey. Reston, VA, United States. 1972.
Document typeMap; Serial; Report
ISSN0160-0753
GeoRef1964-007048
Keywordsareal-geology; Colorado-; geologic-maps; Jefferson-County-Colorado; maps-; Morrison-Quadrangle; United-States; USGS-

Abstract

Potassium-argon ages of sanidines, biotites, and basalts are found to be in essential agreement with time-sequential dating of Tertiary land mammals. A detailed time scale of the Tertiary based on an age breakdown is given.--H.C.W.S

41 samples from this reference

Results Map Plot Download
SampleRock nameMajorTraceIsotope
KA 65Rhyolite
KA 101Andesite
KA 145Tuff
KA 161Not given
KA 175Tuff
KA 305Tuff
KA 320Tuff
KA 321Tuff
KA 328Tuff
KA 414Tuff
KA 449Tuff
KA 451Tuff
KA 452Tuff
KA 453Tuff
KA 478Tuff
KA 480Tuff
KA 482Tuff
KA 482IITuff
KA 490Not given
KA 499Tuff
KA 500Tuff
KA 551Tuff
KA 552Tuff
KA 559Rhyolite
KA 577Tuff
KA 587Tuff
KA 814Basalt
KA 816Basalt
KA 829Tuff
KA 993Basalt
KA 1001Basalt
KA 1003Basalt
KA 1005Tuff
KA 1017Tuff
KA 1026Andesite
KA 1262Tuff
KA 1275Tuff
KA 1365Tuff
KA 1368Tuff
KA 1372Tuff
KA 1380Rhyolite