This book summarises information in dating and correlation of the strata of late middle Eocene through early Oligocene age in North America. The book then reviews almost all the important terrestrial reptiles and mammals found near the Eocene-Oligocene boundary.

Part I. The Chronostratigraphic Framework of the Uintan Through Arikareean: 1. Magnetic stratigraphy and biostratigraphy of the middle Eocene Uinta Formation, Uinta Basin, Utah D. R. Prothero; 2. Biostratigraphy and magnetic stratigraphy of the Bridgerian-Uintan Washakie Formation, Washakie Basin, Wyoming S. M. McCarroll, J. J. Flynn and W. D. Turnbull; 3. Magnetic stratigraphy, sedimentology, and mammalian faunas of the early Uintan Washakie Formation, Sand Wash Basin, northwestern Colorado R. K. Stucky, D. R. Prothero, W. G. Lohr and J. R. Snyder; 4. The Bridgerian-Uintan boundary and the 'Shoshonian Subage' of the Uintan S. L. Walsh; 5. Middle Eocene mammalian faunas of San Diego County, California S. L. Walsh; 6. Stratigraphy and magnetic stratigraphy of middle Eocene Friars Formation and Poway Group, San Diego County, California S. L. Walsh, D. R. Prothero and D. J. Lundquist; 7. Magnetostratigraphy of the middle Eocene Coldwater Sandstone, central Ventura County, California D. R. Prothero and E. H. Vance, Jr.; 8. Stratigraphy and paleomagnetism of the upper middle Eocene to lower Miocene (Uintan to Arikareean) Sespe Formation, Ventura County, California D. R. Prothero, J. L. Howard and T. H. H. Dozier; 9. Magnetostratigraphy of the Eocene-Oligocene transition in Trans-Pecos Texas D. R. Prothero; 10. Magnetostratigraphy of the Duchesnean part of the Galisteo Formation, New Mexico D. R. Prothero and S. G. Lucas; 11. Stratigraphy and mammalian faunas of the Bridgerian–Duchesnean Clarno Formation, central Oregon C. B. Hanson; 12. Eocene–Oligocene faunas of the Cypress Hills, Saskatchewan J. E. Storer; 13. Magnetic stratigraphy of the White River Group in the High Plains D. R. Prothero; 14. Magnetostratigraphy and biostratigraphy of the Eocene-Oligocene transition in western Montana A. R. Tabrum, D. R. Prothero and D. L. Garcia; 15. The Whitneyan-Arikareean transition in the High Plains R. H. Tedford, J. B. Swinehart, C. C. Swisher III, D. R. Prothero, S. A. King and T. E. Tierney; Part II. Common Vertebrates of the White River Chronofauna: 16. Testudines J. H. Hutchison; 17. Squamata R. M. Sullivan and J. A. Holman; 18. Ischyromyidae T. H. Heaton; 19. Cylindrodontidae R. J. Emry and W. W. Korth; 20. Castoridae X.-F. Xu; 21. Canidae X.-M. Wang and R. H. Tedford; 22. Nimravidae H. N. Bryant; 23. Amphicyonidae R. M. Hunt, Jr; 24. Small Arctoid and Feliform Carnivora J. A. Baskin and R. H. Tedford; 25. Merycoidodontinae and Miniochoerinae M. S. Stevens and J. A. Stevens; 26. Leptaucheniinae E. CoBabe; 27. Leptomerycidae T. H. Heaton and R. J. Emry; Summary D. R. Prothero and R. J. Emry.