Major stratigraphic and time divisions in use by the U.S. Geological Survey._ iv Introduction______________________________________ Acknowledgments. _--__ _______ _________________________________ Bibliography________________________________________________ Symbols___________________________________ Geologic time and time-stratigraphic (time-rock) units________________ Time terms of nongeographic origin_______________________-______ Cenozoic_________________________________________________ Pleistocene (glacial)______________________________________ Cenozoic (marine)_______________________________________ Eastern North America_______________________________ Western North
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