CONTENTS. 



Page. 



Introduction 7 



Formations and zones 7 



Life zones 7 



Geologic formations 7 



Correlation 8 



Bibliography 9 



Chapter I. General geologic and climatic history of the Tertiary 19 



The Mountain Region 19 



The Plains Region 20 



Resemblances and contrasts between Mountain and Plains regions 21 



Resemblances 21 



Contrasts 21 



Geologic history of Mountain basin deposits of the Eocene and Oligocene. 24 

 Geologic history of the Great Plains deposits of the Oligocene to lower 



Pleistocene 26 



Extent 26 



History of opinion as to mode of deposition 26 



Summary 28 



Chapter II, Time correlation of mammal-bearing horizons 29 



The two grand problems 29 



American correlation 29 



American and Eurasiatic correlation 29 



Methods of correlation 30 



Bases 30 



Sources of error 30 



Preliminary correlation of the Eocene and Oligocene Mountain deposits. . . 31 

 Preliminary correlation of the Oligocene to lower Pleistocene Mountain and 



Plains deposits 31 



Chapter III. Western American Cenozoic horizons 33 



Eocene 33 



I. First faunal phase 33 



Post-Cretaceous or basal Eocene (etage Thanetien) 33 



1. Puerco formation, Poiy mastodon zone 33 



2. Torrejon formation; Pantolamhda zone 34 



II. Second faunal phase 35 



Lower Eocene (etages Sparnacien, Ypresien) 36 



3. Wasatch formation; Coryphodon zone 36 



3a. Wasatch of the Bighorn basin 41 



III. Third faunal phase 42 



Lower to middle Eocene (etages Ypresien, Lutetien inferieur) 43 



4. Wind River formation; Lambdotherium and Bathyopsis 

 zones 43 



4a. Huerfano formation; Lambdotherium and ? Uintatherium 



zones 48 



3 



