CONTENTS 



Page. 



Letter of transmittal xvii 



Preface xix 



Chapter I. — General geology, by S. 1 . Emmons 1 



Physiography 1 



Mountain topography 2 



Foothill topography 5 



Plains topography 7 



Historical geology 10 



Pre-Cambrian formations 10 



( ambrian land 13 



Early Paleozoic sediments 15 



Carboniferous movement 17 



Wyoming formation 18 



Lower Wyoming 19 



Upper Wyoming 20 



Jurassic movement 21 



Morrison formation 22 



Early Cretaceous mo\ emeni -■'• 



Dakota formation 25 



Colorado formation 26 



Mid-Cretaceous movement 26 



Montana formation 28 



I laramie formation 28 



Post-Laramie movement 29 



Arapahoe formation 31 



Post- Arapahoe movement 32 



1 lenver formation 33 



Post-Denver movement 36 



Monument (reek formation 38 



Later movements 39 



Pleistocene formations 40 



Structural geology •- 



Plains a lea 13 



Foothill structure 45 



